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Got One of These Asus Routers? Sprinkle on Some Merlin Firmware Magic!

No, I’m not talking about wizards, but just regular Wi-Fi tech, which is cooler than magic anyway.

So yes, if you’re interested in making your Asus router (even) better, you’re reading the right post. It’s all about getting your router the Merlin firmware treatment.

Dong’s note: Putting third-party firmware on a router, among other things, can be tricky and even cause the router to die if you don’t do it right. Consider yourself warned. By the way, I have no affiliation with the maker of Merlin. The information posted here is from my personal experience and in no way means I endorse Merlin. Use it at your own risk.

Asus RT AX86U On From Top
The RT-AX86U is the latest Asus router to get the Merlin treatment.

What is firmware?

Firmware is like a mini operating system. Every piece of tech gadget or electronics has to have run on a piece of software. So firmware to a router is kind of like Windows 10 to a computer. It decides how (well) the router functions and dictates what you can do with it.

Firmware vs. operating system

Both firmware and operating systems are software that manipulates the hardware to deliver specific results. But they differ in nuances.

Specifically, firmware has low-level — more direct and crude — access to the hardware. It’s geeky and closely related to a device’s physical components.

On the other hand, an operating system has higher, safer, and more refined access to the hardware. It’s user-friendly and about giving users what they want instead of dealing with hardware components’ basic functions.

A crude analogy: Firmware is like the wiring and switches under the hood of a car, while the operating system consists of the driving wheel, control buttons, and other shiny things inside the cabin. Most drivers only care about the latter and have no interest in the former, which, among other things, will make their hands dirty.

On a computer, the motherboard itself uses firmware, called BIOS, that decides what kind of computer it is and which operating system — Windows, Linux, or macOS, for example — you can install on it and how.

In some situations, though, the line between firmware and an operating system is blurred, and you can call the two interchangeably. For example, the firmware of Synology routers or Netgear’s gaming ones is so advanced that folks call those operating systems.

But generally, devices with limited functions, like the Internet of Things (IoT) gadgets, use firmware. And advanced devices, such as smartphones, tablets, or computers, use an operating system (on top of a firmware layer).

So, for the most part, Wi-Fi routers use firmware. But if you want to call that an operating system, that’s fine with me, too.

Asus WebUI Main
Here’s the web interface of an Asus RT-AC88U running stock firmware. Note the differences when it runs Merlin firmware below.

Stock router firmware

By default, the networking vendor ships their routers its firmware already installed. That’s called “stock firmware,” and in most cases, you can’t change it.

You may be able to upgrade the firmware to a newer/better version once in a while, but for the most part, the router’s features remain the same for the rest of its life.

Asus’s stock firmware, called Asuswrt, is used in all Asus’s home routers released in the past decade. (By the way, WRT stands for Wireless Receiver / Transmitter. It’s a common acronym in Wi-Fi broadcasters.)

Merlin: Special third-party firmware

With some routers, you can put third-party firmware on them. Popular open-source router firmware, such as DDWRT, can work on (select) routers from multiple networking vendors. They tend to be completely different from the stock firmware and, therefore, quite hard to handle.

On the other hand, Merlin is the third-party firmware available only to certain Asus routers. It’s also very similar to Asus’s stock firmware. In fact, you can see it as an enhanced version of Asuswrt. What’s most important, for the most part, Merlin is as easy (or hard, depending on who you ask) to use as Asuswrt.

Merlin Web UI Main
The interface of the RT-AC88U running Merlin firmware. Note the Merlin logo.

The list of Asus routers that can run Merlin

Here is the list of current Asus routers that you can put Merlin on.

  • Wi-Fi 5 routers: GT-AC2900 (beta), RT-AC66U_B1, RT-AC86U, RT-N66U, RT-AC1900, RT-AC87U, RT-AC5300, RT-AC3200, RT-AC3100, RT-AC88U, RT-AC68U, RT-AC66U, and RT-AC56U.
  • Wi-Fi 6 routers: RT-AX56U, RT-AX58U (a.k.a RT-AX3000), RT-AX88U, RT-AX86U, RT-AX68U, and GT-AX11000.

So, as you can see, not all Asus routers can run Merlin. There sure will be more in the future, but we have to wait and see.

In my experience, the RT-AC88U and RT-AX88U are currently the best Merlin options since they have the most to offer. But all the above will work similarly in terms of settings and features.

Merlin firmware vs. Asus stock

Asus builds its Asuswrt using Linux via the GNU Project and shares its source code via GNU’s General Public License (GPL). Then, the Merlin group, led by Eric Sauvageau, changed the source code to create a better alternative. For free. (They do accept support via donation.)

In other words, Merlin is based on the stock firmware and, therefore, always becomes available, if at all, (long) after the release of a router.

Still, it’s not surprising that its official name is Asuswrt-Merlin, though some might call it MerlinWRT. I’d call it Merlin for short. Merlin itself is also open-source software.

That said, generally, Merlin has all the settings and features of the stock firmware and then some. In other words, for a particular router, Merlin encompasses its stock firmware.

Merlin firmware’s features

Merlin TOR
Merlin has more features and in-depth settings than the stock firmware, including the support for TOR.

Here’s the complete list of Merlin’s features, but the short list of benefits includes:

  • Better VPN support, which, among other things, has the ability to route certain clients via VPN or globally.
  • More flexible DNS — you can set the DNS server for individual clients or globally.
  • Built-in TOR support for privacy, with the individual client control, can route certain clients via TOR or globally.
  • More frequent firmware updates, especially when it comes to addressing bugs.
  • Better stability.
  • Lots of control, feature, and automate options via user scripts and add-on packages.
  • AiMesh support (starting with version 384).

Notes on moving between Asus stock firmware and Merlin

Generally, Asuswrt and Asuswrt-Merlin are very friendly toward each other. That means:

  • You can move a router between these two firmware options at any time. Specifically, you can flash a router from Asuswrt to Merlin, and all of its settings will remain the same. The other way around, though, only common settings between the two will remain.
  • You can restore a router using a setting backup file of either firmware. And, just like stock firmware, you can restore the settings of one router to another. In this case, though, depending on the routers involved, some settings might not be carried over.
  • The Asus Router mobile app (made by Asus) also works with a router running Merlin.
  • Overall, Merlin’s web interface looks and feels the same as does Asus’s stock firmware. You might not even notice that you’re using Merlin.
  • The AiMesh feature is available in Merlin (starting with version 384), and you can use routers of either firmware together.

Merlin firmware and AiMesh

Note, though, that you generally want to use AiMesh with the same firmware (Asuswrt or Merlin). Mixing the two, understandably, might lead to unexpected issues. Also, AiMesh is developed by Asus, so Asuswrt is naturally better and more predictable.

But in my brief testing, things were fine when I used Merlin in the primary router, regardless of the nodes’ firmware. When I used Asuswrt in the primary router and Merlin in a node, the performance was fine, but it was impossible to update the node’s firmware successfully.

I’d have to reset the node, load the new firmware in the router mode, and then re-add it back to the mesh. It was a bit of a pain.

See also  AiMesh in 2021: Asus's Ongoing Effort to Excellent Wi-Fi Coverage

But that was about the only shortcoming of using Merlin in my short experience, which wouldn’t exist if you use Merlin throughout or at least in the primary router. Also, the performance of a mixed system proved to be fast and reliable in my brief trial.

Asus’s take on Merlin

Asus didn’t give me any opinion on Merlin. Instead, it only said it provided Asuswrt’s code as an open-source under GPL, as mentioned above.

But the company did tell me one crucial thing: Putting Merlin on Asus hardware will not affect its warranty. Specifically, a representative told me:

“[…] as long as the router does not break/fail during the firmware change process, we will still provide the warranty for the hardware. The 3rd party software is not tested by ASUS, so we do not provide the warranty for the 3rd party software.

In short, there’s no risk in using Merlin as long as you don’t mess up the firmware migration process or expect tech support from Asus.

RT AX88U vs RT AC88U 4
The Asus RT-AX88U (left) and RT-AC88U are excellent candidates for Merlin.

How to manually flash (Merlin) firmware on an Asus router

The good news is that flashing your router from Asuswrt to Merlin is the same as manually upgrading the stock firmware. It’s easy enough.

Literally, all you have to do is download the firmware and load it on the router via its web user interface, just like the firmware update process of any standard router.

The following are detailed steps to manually flash a Merlin or stock firmware file on an Asus router. I used an RT-AC88U unit, but you can apply them to flashing any other model using stock or Merlin.

1. Download the (Merlin) firmware for your router

Here’s the Merlin link for all supported routers. You want to download the latest Release version, though you can also try the beta if you want to be adventurous.

(If you want to use stock firmware, Google the router’s model plus “firmware,” and you’ll find the download page for the router from Asus’s website.)

The download file comes in the .zip format, which is a compressed folder. You first need to open this file (double click on it) and then get the actual firmware file out. The file you want is named after the router’s model and the firmware version.

Merlin Firmware Extract
It’s easy to extract the firmware file from a ZIP folder. Note the router’s model number in the file name.

In my case, I dragged and dropped the file onto a folder called “Merlin” on my Windows 10 computer’s desktop. The point is you need to remember where you put this firmware file.

2. Login to the router web interface

From a connected computer, log in to the Asus router’s web interface. You can do this by navigating a browser to its default IP address, which is often 192.168.50.1, or router.asus.com.

RT AC88U Firmware Update
On the interface of an Asus router, you can quickly jump to the firmware upgrade section by clicking on the firmware version itself.

You’ll be asked for the username (“admin” by default) and password, which is the one you created when you first set up the router. Once logged in, go to:

Administration -> Firmware Update

Alternatively, you can click on the firmware version at the top of the interface’s webpage to jump to the firmware update section. Now you’re ready to perform the firmware migration in the next step.

3. Upload the Merlin firmware

Click on the Upload button (see screenshot below). A dialog will pop up for you to navigate to the location on the computer that holds the firmware file. In my case, the location is the “Merlin” folder on the desktop, as mentioned above.

RT AC88U Firmware Upload
Navigate to the location of the Merlin file and choose to open it.

Now double click on the (Merlin) firmware file, or select it and then click Open. The flash process will start immediately.

Important: This process will take a few minutes. During this time, make sure you leave the router and the web interface alone. Don’t unplug the router or the computer from the power!

RT AC88U Firmware Progress
The upgrade/migration process will take a few minutes and needs to be left alone.

After that, the router will restart itself, and the webpage will go back to the login page. Log in to the interface again, and you’ll now see the Merlin logo on the top left corner of the web page. You’re almost there.

asuswrt merlin
The Asuswrt-Merlin logo.

Now manually restart the router one more time by unplugging it from power, wait for a few seconds, then plugging it back in. (You can probably skip this step, but in my experience, a manual restart is always helpful after a firmware change. So do it!)

And that’s it. Mission accomplished.

If, for some reason, you want to switch back to Asuswrt, repeat the steps above, using the router’s stock firmware. Again, either way, the settings will (largely) remain.

Merlin firmware: The take away

Everyone will enjoy the better stability Merlin brings to an Asus router. But for the most part, Merlin is a geeky option for advanced users. It opens up many possibilities. In return, it requires a bit of networking know-how handle — it’s not a must-use.

But I know many advanced users who only buy an Asus router after Merlin is available for it — and I don’t blame them. If you can appreciate even just one of the many benefits this alternative firmware has to offer, such as the vastly more advanced VPN feature, it’s tough to go back.

One thing is likely: If you have a supported Asus router that doesn’t work as well as you’d like, putting Merlin on it will, well, magically make it a lot better. Try it. You have nothing to lose.

See also  Best Wi-Fi 6 Routers of 2021: Take One, or Two, Home Today!
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66 thoughts on “Got One of These Asus Routers? Sprinkle on Some Merlin Firmware Magic!”

  1. Hi Dong,

    I’ve got a stock Aimesh setup of 3 different routers 86u main + 68u and 66u_b1 as nodes. All working fine. I’ve bought an additional 68u from eBay (which was previously on Merlin but the seller flashed it back to stock before sending) to add to this but the main router refuses to see it. I’ve checked the firmware, reset the node, and made sure they are close together but nothing is making the main node find the new one.

    So a couple of questions:

    – is it possible that the new 68u has been “messed up” in someway (how do i check!) – I’ve got another 68u on its way from Amazon in order to check if that works or prove it’s the main node.
    – is there any chance flashing Merlin into the main node might help?

    Reply
    • I can’t comment on stuff you bought from eBay, Steven. You need to check with the seller. And no, Merlin generally won’t improve AiMesh since it’s an Asus feature. On this front, Merlin is a step behind.

      Reply
      • Thanks for the reply, I’m not after a comment on the “stuff I bought on ebay”, I was just asking whether you knew of any mods when switching to Merlin that might impact the ability of the master node to “see” a child. I read somewhere about Mac address being altered but can’t find it now!!!

        Reply
          • I disagree. Merlin works fine with Asuswrt nodes and vice versa. There’s no technical reason why it should not, as the same AImesh coding is used all over. As for nodes not being reckognized, I would suggest factoryreset, followed by temporary cable bacbone (whilst doing setup).

  2. I enjoy reading your articles. Thanks. Just one question. After installing Merlin software, will “Network Protection powered by Trend Micro” will stay (or does it get removed)?

    Reply
    • Yes, it’ll stay, Raj. Like I mentioned in the post, it generally has everything Asuswrt has in terms of features and settings, and then some.

      Reply
  3. Hi Dong,
    You mention the ac88u has the most to offer with Merlin over the other Asus routers. What Merlin features would you say it has over the ac86u which I understand to have a faster CPU.

    Reply
    • I didn’t say that, Chris. Also, it’s not just the hardware specs that matter, but also how mature the firmware is for the models.

      Reply
      • Hi Dong,

        It was the line “In my experience, the RT-AC88U and RT-AX88U are currently the best Merlin options since they have the most to offer.” that made me think the ac88u had some special Merlin features not available to others. Firmware to hardware maturity makes sense thanks!

        Reply
  4. It’s been about 4 years since I last used Merlin. I’m in the market for a new router to replace my 4 year old router that’s failing. Looking at picking up an Asus of some sort.
    Does the latest Merlin have the ability to connect to a IPSEC L2TP VPN server and to route traffic for certain subnets through that tunnel?

    Reply
    • No ipsec l2tp vpn client on my 86u running merlin, i only saw ipsec l2tp as server. At lease openvpn speeds are very fast but not as fast as wireguard which is only available with ddwrt and openwrt supported routers.

      Reply
  5. Many thanks for another great article. Now that Merlin does AiMesh 2.0 and I have 3 XT8s in service with the somewhat skittish current AsusWRT official firmware, I sure wish we could get some Merlin magic for that model! Any ideas whether that’s a possibility?

    Reply
  6. Dear Dong

    I use my VPN Client a lot, I have an old Netgear Router, it has become slow and I constantly keep getting disconnected. So I want to buy an Asus Router and install Merlin on it to improve my overall connection quality, but mainly to have the VPN installed on it directly and active 24/7. My idea is to open two tunnels, one with VPN and one without VPN depending on the device that I use to connect with, to make it practical.

    I was thinking between the Asus RT-AC86U and the Asus RT-AC-88U. You have mentioned in your posts that you own and love the RT-AC88U because of it’s 8 ports, link aggregation, etc, but I was wondering if in my specific case where I need the VPN to work well, the better, newer processor of the RT-AC86U would make it a better option.

    Thanks so much for all the information you share with us, it is really very valuable.

    Reply
    • OpenVPN is very CPU hungry. I would go with the faster CPU. I have been using the Asus RT-AC86U since May 2018, mainly for the VPN (as you want to), with Merlin Firmware.

      Hm, it was working well, but with the VPN on 24/7 it was freezing sometimes when the network traffic was high. Also, periodically I had to re-import the VPN settings file, because it didn’t connect anymore.

      I upgraded to the AX11000 in Jan 2021, as it had WiFi6 and had VPN Fusion, and has much stronger CPU.

      So far, it worked more or less well, but sometimes it stops giving the internet access. Everything else works, just no internet. I need to reboot it. I suspect it is because of the VPN.

      {Suspected spam link removed}

      The Merlin readme suggests to manually reset the router and enter the settings after every 3 firmware updates.

      Reply
  7. I installed the latest Merlin firmware for the AC88U. A message popped up saying to manually reboot the router.
    I did this but.now I can’t find the router admin login page. When I try router.asus.com all I get is a blank white page saying scripts.affiliatefuture.com.
    I tried the IP address in the guide and that doesn’t work either. How do I find the correct addres to get back in

    Reply
  8. I had been running Merlin that was about 6 months old, so decided to update to RT-AC68U_386.1_2.zip. Well, now I can’t get into the router. When I go to 19.168.1.1, I just get a white screen in my browser (Firefox). So no menu, no way to downgrade, can’t access. What should I try next?

    Reply
  9. – Great article.
    – However in regards of Merlin on AIMesh nodes, here is Eric Sauvageaus own words:
    “While Merlin-based nodes seem to work fine so far, there is generally little benefit in running it on a node, so it’s generally recommended to leave your nodes on the stock Asus firmware.”
    ( https://github.com/RMerl/asuswrt-merlin.ng/wiki/AiMesh )
    – Hence it is a bit misleading in your article to advise Merlin on all nodes.

    Reply
    • Thanks, Torbjorn. I don’t work with Eric. What I described was my experience. As I mentioned, mixing the firmwares is fine, but you’ll likely have minor issues (like with the firmware update).

      Reply
  10. I have a question, Dong re: 86U, the file is w format not trx does it matter? also in changelog it says partition jffs, what’s about it? Do I need to do that

    I have latest asuswrt firmware releases on Jan 11,2021

    Thx any help is appreciated

    Reply
    • You don’t need to use Merlin, Hresch. But if you want to use it, it’s a better idea to spend some time and educate yourself on what jffs (and many other things) mean, but you can ignore it. To answer your question, the file type of the firmware file doesn’t matter.

      Reply
  11. Dong! thanks to your advice and reviews, I’ve purchased an ASUS rt-ax88u, it runs amazing with a gigabit connection. Still, I want to get into AiMesh, the signal strength in the basement is weak. Any advice on what Asus router I should use as the Node?

    Best,
    Ali

    Reply
  12. Three months later and I am complaining about your idea of what firmware is?
    Maybe not great but still, your explanation is WAY OFF BASE.

    Firmware is just the same as software. It could be an OS or just a set IO controls like BIOS. What makes it FIRM rather than SOFT is the fact that it is “burned” onto a chip, so that it is “hardware” not “software” but with PROM technology even that distinction is blurred as you can, and do, “reburn” your firmware chips regularly.
    Your idea of an OS sounds more like a UI than an OS.
    You could burn an entire OS, and include a UI, onto a PROM an have it all in firmware.

    Reply
    • Thanks for the input, Don. I love it when somebody complains. I mean it.

      But take another read at the post. I clearly stated that firmware is low-level and has direct access to the hardware. That’s way easier for anyone to understand than saying it’s “burned” onto a chip, which is not exactly correct, to begin with. (And then I would have to explain what a chip is, too.) I was busy trying to make folks have an overview of what firmware is vs. OS (which, by the way, always accompanies any new computer you buy) than trying to show off what I know. And the post wasn’t about firmware in general but mostly about a particular one.

      Reply
  13. Hi, I installed Merlin on Asus RT-AX86U. But I am unable to config VPN. I tried talking to the representatives of VPN provider but still no luck after spend 3-4 hours.. Any advice, suggestions or solutions? Thanks in advance.

    Reply
    • You made me laugh, Jai. To get help, you first need to know HOW to ask for help first. Judging from the way you asked the questions, I think it’s best to hire a professional to your house who can see things and figure stuff out for you. 🙂

      Reply
  14. Appreciate the article and am looking to update my Asus RT-AX58U. I do have a second RT-AX58U as a node. It is unclear to me how to update the node first as you indicated. How do I flash the node when I cannot login into it directly?
    Thanks.

    Reply
    • You do that via the router unit’s Interface, Stuart. The step is the same as mentioned in this post, just click on the Upload link of the node (instead of the router.)

      Reply
  15. After reading the forums it looks Like even with Merlin the ASUS routers cannot have more than 16 devices assigned to parental controls or be blockable at any one time.

    I need a great router with a mobile app, vpn client capabilities, and support for many more devices in parental controls that can be blocked by a schedule and by a command or switch. Please point me in the right direction. A more business oriented device is fine if it can do what I need.

    Reply
      • Good morning Dong,

        Thanks for replying. I’m not sure where your thought process lies regarding the MAC address comment. With 4 kids from 7 to 18 in the house, they have a lot of devices in the house to use to create distractions. Computers, laptops, tablets, phones, game systems, VR headsets, the list goes on. And there are some last gen phones, game systems and usb wifi adapters as well. I could get by with a 32 device limit for parental controls, but this information is very hard to find. I’m still not 100% sure what the new limits are for ASUS GT-AX1100. I thought I read that the new generation would support 64 devices in parental controls but now I can’t find that information again. I bought a RT-AX92u under that impression but I was mistaken the limits are still 16.

        Ubiquiti told me there is no limit in their OS but I think you mentioned it was sparcely featured. but they have a mobile app.

        The other feature that is a must is the VPN client which can route selective hosts via the VPN. VPN Fusion from ASUS has worked well, and Merlin has it via Entware on its supported devices.

        If I have to forgo a mobile app to get what I need I will have to, but these other 2 features are a must. Any direction you may have is really appreciated.

        Reply
  16. Great article as usual. I had Merlin on a previous router and would LIKE it on my current AC88U, but I have two AIMesh nodes. It wasn’t clear to me if the nodes will automatically update along with the router or if there are other steps although the article seemed to indicate it works with the nodes. Can you clarify for me?

    Tom

    Reply
      • Ach, I’m probably screwed, my nodes are RP AC-1900 so not supported? How much of a hassle is it, or does it even work, to run Merlin on the router and ASUSWRT on the nodes? IF it worked, one would have to upgrade nodes manually from then on?

        Thanks,
        Tom

        Reply
        • Not much of a hassle to get it work, Tom. And yes, you just need to update the node manually as I mentioned OR revert the router to Asuswrt, update the node, then put Merlin on it again. You can back up the settings and restore before and after. Not that bad.

          Reply
  17. To your point on firmware vs. OS, one note is that Merlin allows you to use Entware which includes 2500+ linux packages easily installable via a package manager (okpg). Hook up a USB drive and you have a credible little Linux box on your hands. Recently I ran across an addon that let’s your run scheduled speed tests (so you can see how slow your cable provider really is…) and includes a nice little UI (https://github.com/jackyaz/spdMerlin).

    Like @ChuckD, I’ve been running it for a while and it has been flawless.

    Reply
    • Thanks for sharing, Jim. Yeap, I’m aware of Entware but just didn’t want to be overwhelmingly geeky and get into a territory that’s very hard to explain in layman’s terms.

      Reply
      • HEllo Dong.. thanks a lot for all your explanations… perfect, simple, very cool. Is it possible for you to do the same with the utilisation of “amtm – the Asuswrt-Merlin Terminal Menu”. It will be very very interesting for a lot if guys. Thanks a lot

        Reply
  18. I ran Merlin on my AC68U for five years or so in a household environment and was very pleased with how it did. I especially liked the fairly frequent updates as they often dealt with security issues.
    Be sure to throw Eric some change too, he’s a dedicated volunteer!

    Reply

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