5GHz Wi-Fi is fast, but it has a persistent disconnection issue you may not realize affects your connection. That’s right: your 5GHz Wi-Fi is delivering the wireless internet goods, but it’s also responsible for some of those random dropouts you can’t really explain. You know when your Wi-Fi drops mid-call or mid-stream without warning?
The 5GHz DFS channels could well be what’s causing them, which is why switching them off or blocking them could instantly stabilize your Wi-Fi connection.
5GHz Wi-Fi is broken down into multiple channels
What’s more is that you can’t even use all of them
When it comes to Wi-Fi, you’ll often be advised to move your most demanding devices to the 5GHz band. It has more channels, which should mean less congestion, not to mention it can deliver faster overall throughput. On that, it’s not bad advice, in the slightest.
However, what most advice fails to mention is that while 5GHz has more channels and a broader spectrum than the venerable old 2.4GHz band, it does come with a caveat: your channels are more broadly split than they first seem, almost into four smaller bands.
In the US, the split runs like this: U-NII-1 (channels 36, 40, 44, and 48), U-NII-2A (52, 56, 60, and 64), U-NII-2C/2E (100 through 144), and U-NII-3 (149 through 165). The channels in U-NII-1 and U-NII-3 are yours with no strings attached. The ones in the middle — 52 through 64 and 100 through 144 — are DFS channels, and they come with a condition.
Your router shares its airspace with radar
That’s not ideal, obviously
Tashreef Shareef / MakeUseOf
Now, DFS stands for Dynamic Frequency Selection, which is a core part of the 802.11 standard, otherwise known as Wi-Fi. It exists because most of what we think of as “the Wi-Fi spectrum” isn’t really exclusive to our smartphones, laptops, and smart TVs.
Instead, it’s shared with all manner of devices and other services, all of which can cause and be impacted by interference. Long before a router was considered de rigueur in every home and office across the land, that part of the spectrum was primarily operated by the military, weather radars, airport radars, and similar. Basically, a whole lot of services that don’t take kindly to interference.
That means that before your router confirms that it can use a Wi-Fi channel, it runs what’s known as a Channel Availability Check. This means it checks the selected channel for 60 seconds to confirm that there are no active radar transmissions taking place before it begins broadcasting your signal.
No radar, and everything is up to scratch. Your Wi-Fi connection is good to go. But if there is radar activity or otherwise, the router will re-scan the airways to find another option.
That’s not the only issue with DFS channels. Your router doesn’t stop scanning for radar transmissions. Instead, it actively scans in the background, and if it detects one, it’ll boot you from the channel and reassign you. When that happens, as you might expect, your devices are also all booted from the channel and forced onto another, regardless of your other settings. You also can’t return to that channel for 30 minutes!
The frequency with which you’ll get pinged really depends on where you live. If you’re near the coast, an airport, heliport, port, weather station, or similar, you’ll likely notice these 5GHz Wi-Fi band rejigs more often than, say, someone who lives alone in the middle of nowhere.
How to check if you’re using a DFS channel
Head to your router admin panel
The quickest way is to head to your router’s admin panel, where you’ll find a Wi-Fi menu detailing the current Wi-Fi band and channel. If your 5GHz Wi-Fi channel is using 52 through 64, and 100 through 144, you’re sitting on the DFS channels.
However, that doesn’t immediately mean you have to change. If your router hasn’t automatically moved you, it’s likely you’re outside of any radar interference.
But if you’re experiencing frequent dropouts, it’s worth switching to different channels on the 5GHz band.
The easiest way to block DFS channels is manual selection
Head to the router admin panel and select the best option
If you want to avoid the DFS channels completely, the best and easiest option is to set your Wi-Fi channel manually. Most routers have an automatic Wi-Fi channel selection option that, when disabled, allows you to set the channel manually.
Furthermore, some routers have a specific DFS channel on/off option you can toggle. This isn’t the same across all routers, so you’ll have to search the router options. But once toggled, the auto-selector stops considering those channels at all.
There is one final consideration to blocking DFS channels on your router for good: you won’t be able to maximize channel width to 160MHz due to the limitations of overall channel width. With each channel being 20MHz wide, you’ll butt up against a DFS channel if you want to extend to 160Mhz.
While that sounds like a limitation, you can still use 80MHz bonded channels quite happily, and most importantly, without causing network instability. A stable 80MHz connection beats a 160MHz one that resets itself multiple times a day.