Question Regarding Bandwidth Settings, 160MHz, and DFS

[AntonK]

I’m probably setting myself up for some hearty guffaws with this question, but I’ll put it out there anyway. I know DFS is discouraged in an environment where you might be in fairly close proximity to an airport or weather radars. But are the selections below (to include 160 but not DFS channels) a reasonable setup? I’m a simple home setup. Thanks.

 

[tgl]

I'm assuming you're in the USA; the answers will differ elsewhere.

You can get a 160MHz channel centered on 163 (and thus 157 is a valid control channel for it), but that requires use of the "U-NII-4" channels above 165, which were only rather recently opened for wifi use by the FCC. Recent Asus kit does support that, but will your clients? See wikipedia's table of 5GHz wifi channels here, and test to see if you're actually getting 160MHz bandwidth on the clients you care about.

One other comment is that I learned the hard way not to trust the "exclude DFS channels" checkbox in AIMesh. Maybe they fixed that bug recently, but personally I always set the control channel manually.

 

[MDM]

I live in a Capital city in Europe (Belgrade, Serbia) - so NOT EU, but my router is EU...
Airport is at 13km, military airport 20km, national weather station 7km (not in direct view - over a hill), and airplanes passing over my head (not that low usually - am not on the flight path).

With latest Merlin FW (since alpha's new GPLs WiFi drivers), full DFS:

 

[tgl]

It's really a YMMV situation. In my old house, about 16 mi/25km from the airport and a similar distance from the weather radar station --- with some substantial hills between --- I thought that using DFS channels wouldn't be a problem. I was very wrong. Maybe the topography made those hills less helpful than I expected, or maybe the ASUS XT8s I was using were set up to drop DFS more quickly than they had to, or who knows? But the system was completely unreliable until I disabled use of DFS.

My new digs are only about 10mi from the airport, and smack on top of one of the larger of the aforesaid hills. So I haven't dared to even think of trying DFS here. I do see from WiFi Explorer that some of my new neighbors are using DFS channels, but I wonder what sort of reliability they get. (I get the impression that those SSIDs bounce around to different channels a lot, which would suggest that it's not great.)

Having said that, other people do report successful use of DFS channels. So give it a try, and keep an eye on your router logs to see how often you get the dreaded "RADAR detected" message.

 

[MDM]

It was awful for me too with old WiFi drivers - 1-2 h at best, sometimes only 10minutes!
Since, practically NO false-positives

 

[OzarkEdge]

I’m probably setting myself up for some hearty guffaws with this question, but I’ll put it out there anyway. I know DFS is discouraged in an environment where you might be in fairly close proximity to an airport or weather radars. But are the selections below (to include 160 but not DFS channels) a reasonable setup? I’m a simple home setup. Thanks.
View attachment 52929

I'll take a stab at it... yes, reasonable.

Exclude DFS control channels if you have a legacy client that cannot use them... can not connect. This restriction does not necessarily prohibit the router from using near DFS extension channels with a non-DFS control channel to achieve max bandwidth for a given connection... so, DFS extension channels may still be in play and subject to DFS action. It helps to know how the spectrum is to be utilized in your region.

20/40/80/160MHz bw allows the router to vary its max bandwidth permitted to restrict spectrum use to reduce/avoid radio interference. I call this unfixed or auto bandwidth. For given control and extension channels, if 160MHz encounters noise, then the router can drop to a lower max bandwidth to avoid the interference.

Or, you could set a fixed max bandwidth 20, 40, 80, or 160MHz and hope that clients do not encounter noise... but if it's RADAR/DFS noise, the router must do what it takes to vacate the DFS channels... restrict/narrow the bandwidth even though you fixed it at 160MHz (and/or vary the control channel).

Similarly, Auto ch allows the router to vary its control channel to reduce/avoid radio interference. I call this unfixed or auto control channel.

My WiFi environment is not crowded, so I prefer to fix both bw and ch to minimize auto disruptions and to encourage neighboring WiFi on ch Auto to move out of my way. I'm currently using non-DFS ch 36 at 160MHz bw (U-NII bands 1 and 2a). Clients connect at their max bandwidth permitted by the router. A DFS event that requires vacating DFS band 2a will drop the router max bandwidth to 80MHz (non-DFS band 1).

Speaking of noise, today I noticed that my Wireless Log 2.4 ch 11/20 noise level increases from -97dBm to -84dBm whenever the microwave oven is turned ON. This interference also audibly disrupts Bluetooth speaker connections. I wonder... if I were using auto settings, would the occassional microwave interference cause the router to vary ch/bw to avoid it... disrupting all wireless client connections?

OE

 

[jata]

My 2 cents on this is...

I have everything working well with 5G channel 36 fixed at 160MHz with 388.4 merlin. My nodes and capable clients all connect at 160MHz. No interference. No DFS events but... I don't see any real world speed difference on my network (1G LAN).

I find it annoying waiting for the 5G to clear for radar on restart of wifi change so I am happy with channel 36 fixed and 80MHz.

 

[MDM]

I use channel 100 instead of 36 because the signal is noticeably stronger, and the higher band i less occupied for me.
I also noticed long ago that when fixed at 100/160 (or 100/80 with old router), that made all the neighbors routers flee and free that space (all on auto I presume) after a day or so. So there is a bonus reason to have any channel fixed, as you in a way reserve the space in the ether...

 

[bbunge]

As you have found, you will get lot of works for me answers. So, one more..

Over the last three years I have run my AX routers with just about every channel and bandwidth combo. All worked sort of. Now I am on Auto Channel, DFS Enabled, 80 MHz bandwidth and WPA2 personnel. All of my clients are happy and WIFI and Ethernet file transfers to and from the NAS seem equal. The 5GHz has been at channel 140 since the last reboot a week ago.

While it is a badge of honor to be able to run 160 MHz it is more important to have stable connections.

But, your milage can vary. It is your environment that will determine what you can do. Auto channel, DFS enabled at 20, 40, 80, 160 MHz is a good place to start and let the router choose what works best for it.

 

[OzarkEdge]

Auto channel, DFS enabled at 20, 40, 80, 160 MHz is a good place to start and let the router choose what works best for it.

I think a good place to start is no DFS and 80 MHz max bw. If you want to work it and learn, use fixed settings and make observations; otherwise, use unfixed/auto settings (set and forget). Once you have a feel for using your clients in your radio space, then experiment with DFS and more bandwidth.

Why experiment? To move your network usage forward with the advances in hardware and standards... the sooner you can incorporate new features/capabilities/security, the better, imo (except avoid the leading/bleeding edge!). Sure, you can survive on WPA2 and no ax for the foreseeable future, but this proves nothing and leaves your network stuck in time while your clients/guest clients continue to advance. If a client hiccups, then you can knowingly throttle network settings back to accomodate it... or retire that old client to keep your network ready and able and moving forward.

Unfortunately, ASUS makes all of this more difficult by releasing buggy firmware... more so recently than previously, imo, due to the introduction of AiMesh and the squirrely nature of the WiFi6/6e/ax standard(s).

OE