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Dual-band vs. Tri-band Wi-Fi and that Burning Bandwidth Question

Dual-band vs. Tri-band Wi-Fi: You can’t tell the Netgear RAX120 (left) from the Netgear RAX200 apart, appearance-wise as well as in terms of Wi-Fi performance (in most cases). Dong Ngo | Dong Knows Tech

I’ve received many questions about dual-band vs. tri-band Wi-Fi routers lately, especially since the reviews of the Netgear RAX200RAX120, and Asus GT-AX11000RT-AX88U. Questions along the lines of “which to get if money is not an issue?”

So, I’ll explain the differences between them in this post. But if you’re in a hurry, here’s the gist: It doesn’t hurt to go with a tri-band router, and in some rare cases, you can even say you need one. Most of the time, though, investing in tri-band is as good as flushing some cash down the drain.

OK, let’s start with dual-band.

Dual-band Wi-Fi: Why do we have it?

Dual-band goes back to the 802.11n Wi-Fi standard (called Wi-Fi 4 nowadays). Things were still simple then, and dual-band routers came into existence because we needed them.

READ MORE:  Networking Your Home Properly with these Wi-Fi Basics

Indeed, initially, Wi-Fi started with only the 2.4GHz frequency band, which was, and still is, too ubiquitous. Apart from Wi-Fi devices, cordless phones, and home appliances (like microwaves) also use this frequency. It’s saturated.

Available to too many applications, 2.4GHz generally suffers heavily from interferences. Soon after the introduction, it quickly proved unreliable for Wi-Fi in urban areas and has remained that way.

That’s when the 5GHz came into play. This frequency band, for the most part, is dedicated to the use of Wi-Fi and has much higher wireless speed.

For a short period, 5GHz was available in 802.11a Wi-Fi standard and offered as a single-band solution as the counterpart of — that could even slowly replace — 2.4GHz. But due to its shorter range, the then not-so-super-fast speed, and the fact that there were many 2.4GHz-only clients, 5GHz couldn’t manage to survive on its own — nobody wanted a 5GHz-only router.

As a result, starting with Wi-Fi 4, we’ve always had dual-band: The co-existence of 2.4GHz and 5GHz. A dual-band Wi-Fi router delivers both performance and backward compatibility. Everyone is happy.

Tri-band: It’s all about the bandwidth

To understand the idea behind tri-band, we first need to know how a router’s bandwidth works. Take the Asus Bue Cave, for example; it’s a Gigabit dual-band AC2600 router.

Gigabit means its network ports (four LANs and one WAN) cap at 1 Gbps (1000 Mbps). AC is short for the 802.11ac standard (or Wi-Fi 5). And 2600 is the rounded combined bandwidth of the router’s 1733Mbps speed on the 5GHz band and 800Mbps on 2.4GHz band.

Since a Wi-Fi client can only connect to a router using one band at a time, the best wireless connection you can get out of the Blue Cave caps at 1733Mbps.

But that’s only when there’s just one client. If you have two clients connecting and being active at the same time, each gets only half of that bandwidth. If you have ten simultaneously active clients, each now connects at only around 170 Mbps; or 17 Mbps if you have 100 clients. You get the idea. And generally, a home router can host up to 253 clients.

A tri-band router has double the bandwidth on the 5GHz frequency, compared to a dual-band router.

So to increase the bandwidth, in 2014, chip makers decided to add another 5GHz band. A tri-band router now has double the bandwidth on the 5GHz, compared with a dual-band like the Blue Cave above. And networking vendors loved this. A higher number means a better marketing tool.

Router bandwidth: Wi-Fi vs. Wired

It’s worth noting that the wireless speed mentioned above is the theoretical rate. In my experience, a 1733 Mbps Wi-Fi connection in real-world usage delivers a sustained speed of around 1000 Mbps.

Using radio to transmit data Wi-Fi is susceptible to interfaces and therefore has a lot of overheads.

And that’s why wired connections are generally superior in terms of throughputs. A Gigabit connection via a network cable has a sustained speed of almost 1000 Mbps.

In other words, the net rate of a wired connection is about the same as its ceiling speed. Among other things, the wires inside a network cable are shielded from the elements, and therefore can work unhindered. 

In a router (or switch), the network ports don’t share the bandwidth. Each port delivers its full rated bandwidth even when all of the ports are active. So, if you copy data from one Gigabit device to another, the speed in between them is still 1 Gpbs.

But wired networking has one major disadvantage, you need to use wires. And that alone means it can’t beat Wi-Fi.

Dual-band vs. tri-band Wi-Fi: The reality

The first tri-band router, as far as I know, is the Netgear R8000 Nighthawk X6. I remember reviewing it in my past life and having a hard time figuring out a way to demonstrate the need for the second 5GHz band.

Frustrated yet curious, I got one for my personal use — I still have it. For several subsequent years, I still couldn’t find any clear advantages of having the other 5GHz band. I gave up and put the router in storage.

My Netgear R8000 Nighthawk X6 router straight out of storage. It’s one of the first tri-band routers on the market. Dong Ngo | Dong Knows Tech

And that’s just the way it is. In real-world usage, you’ll probably see no difference between dual-band vs. tri-band Wi-Fi routers. The first reason is that chances are you don’t have that many active clients anyway.

Connected clients vs. active clients

As mentioned above, a router’s Wi-Fi bandwidth is divided between active clients — those that are sending or receiving something. You can have hundreds of connected clients but only the active ones that count.

The faster a Wi-Fi connection is, the shorter a client remains active — it needs less time to finish transmitting the same amount of information. For example, as you’re reading this, it’s likely that your computer (or mobile device) is no longer active since the post has been fully downloaded. So, in a typical home, chances are you’ll have just one or two active clients at any given time.

And even when you have lots of active clients, how taxing they are on the Wi-Fi pipe also depends on their tier of Wi-Fi, the application they use, and the Internet speed.

Wi-Fi tiers

The numbers I mentioned in the Blue Cave example above were that of the highest 4×4 Wi-Fi 5 clients. In most homes, though, chances are you’ll use clients of different Wi-Fi speed grades and standards.

For example, if you use a 2×2 Wi-Fi 5 clients, its speed already caps at 867 Mbps, even when it’s the only connected client. If you use a 2×2 Wi-Fi 4 clients, this number is 450 Mbps at most. So on and so forth. Also, some clients use the 2.GHz band and put no load on the 5GHz frequency at all.

So, not all active clients use the max amount of bandwidth available at the router’s end, even when working at capacity.

Applications

And Wi-Fi clients tend not to work at capacity. That’s because most applications only need a certain amount of bandwidth. You can make more available to them, but that won’t translate into a better user experience. It’s the law of diminishing returns.

Take movie streaming, for example, a 4K stream requires 25 Mbps and won’t use more than that. So the Blue Cave router’s 5GHz band alone can theoretically handle some 70 Wi-Fi concurrent clients streaming 4K content. Add another 32 clients on the 2.4GHz band.

The actual number of possible simultaneous streaming clients are fewer in real-world usage, but still, any dual-band Wi-Fi 5 router can deliver a lot more than a household would ever need.

Internet speed

The broadband speed is likely the main factor that renders tri-band overkill. That’s because we use Wi-Fi mainly as a bridge to the Internet. And since Wi-Fi and Internet are two different things, faster Wi-Fi doesn’t necessarily translate into speedier Internet access.

Click the Go button above and do a test right now, and you’ll get an idea of how fast your Internet currently is. (If you want to make sure, check out this post.)

Let’s say your broadband is 150 Mbps, which is quite decent. When you have ten Wi-Fi clients accessing the Internet at the same time, using the same application, each of them will be allotted with15 Mbps.

And even if you have just one client, 150 Mbps is still much lower than how fast Wi-Fi can be in general. That said, no matter how much more bandwidth you add to your Wi-Fi, you can’t access the Internet any faster.

The point is, chances are the broadband connection will be used up way before you have to worry about your local Wi-Fi’s speed. Consequently, getting more Wi-Fi bandwidth doesn’t do anything, other than making you a bit poorer.

When a tri-band router is useful

There are few instances where a tri-band router makes sense. Clearly, first, you need to have a lot of 5GHz clients to even think of using a tri-band router. And then, make sure you have at least one of the following to make the investment worthwhile.

  • Compatibility: This might be the most apparent use of a tri-band. You can set one 5GHz band to support top speeds and the other to work in compatibility mode for legacy clients. However, this was useful mostly when 802.11g and older clients were in use. These old devices have mostly been phased out by now. Wi-Fi 4 and later clients generally come with technologies that allow them to work well in a mixed environment, without slowing down one another.
  • Heavy local Wi-Fi network usage: You have an extensive network that uses Wi-Fi, instead of wired connections, for local tasks. Examples of these include network backups, file sharing, photo/video editing. In this case, make sure all clients, including desktops, use the fastest Wi-Fi tier.
  • A super-fast broadband connection: If you’re one of those lucky who has a Gigabit-class broadband connection, then a tri-band router is also useful in maintaining the high broadband speed to more clients at the same time. Again, keep in mind that online applications generally require only so much of bandwidth to work well —  much less than 1Gbps in most cases. The only time faster is always better is when you download a large file.
  • Wireless mesh setup: This is when you use a Wi-Fi connection to link hardware units of a mesh Wi-Fi system together. In this case, you can use the second 5GHz band as the dedicated backhaul. Keep in mind that most standalone tri-band routers do not have a built-in mesh function — they only work as a single router. So far, only those from Asus and Synology can work as part of a mesh system.

Dual-band vs. tri-band Wi-Fi: The takeaway

As you can see, strictly from Wi-Fi’s point of view, there’s almost no scenario you’d need a tri-band router. In some extreme or unusual cases, a tri-band router would help, but still not a must-have. A good dual-band router will always suffice.

But, on the other hand, I don’t see any instance a tri-band router would hurt, either. So, in the end, it comes down to cash. If you can afford it, I’d say go ahead and proceed with one. It’s always nice to be able to turn things up to eleven. 

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About the Author: Dong Ngo

Before Dong Knows Tech, I spent some 18 years testing and reviewing gadgets at CNET.com. Technology is my passion and I do know it. | Follow me on Twitter, or Facebook!

4 Comments

  1. Thanks for the reply, Dong! I do appreciate the features of the RT2600ac (not least of which the 4 LAN ports), so I’ll have to think about the pros and cons of using the RT as base and 2x MR as satellites, vs 3x MR.

  2. Hello! I’m wondering about the effectiveness of using a primary router with just dual-band while having mesh satellites with tri-band (such as with a Synology RT2600ac + MR2200ac combo that you have previously recommended)? The MR2200ac has that 3rd radio for a dedicated backhaul, but the RT2600ac only has the two radios, so will the effectiveness of the system be reduced compared to having both primary router and satellite be tri-band? I

    I currently have an Orbi RBK50 with a single satellite, but I actually need one more satellite to get my network to two desktops in a living room. So I’m considering the pros and cons of adding an additional RBS50 satellite or switching to a Synology system with router and two satellites (I can repurpose the Orbi system for a family member). A dedicated backhaul is important for lowest lag to the two desktops. Curious what you would recommend.

    1. You can use an MR2200ac as the main router in a Synology setup, Ken. When using the RT2600ac as the main router, the band used for backhaul will also serve the client. As a result, the more client connects to it at the same time, the less effective its backhaul connection is since the bandwidth is shared.

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