5Ghz Wifi disappearing on Asus router (channel bandwidth?)

Gnome10

New Around Here
I live in an extremely congested wifi environment. I don't even use the 2.4Ghz band except for low bandwidth devices.

I was doing some reconfiguration yesterday with my new router (Asus RT-AC66U_B1). I have, up to this point, relied on a AP RT-N66R router for best signal, and put it in the center of my apartment (yes, congestion is so bad here, we need a separate access point).

During the day (when most people here are away), I started testing. Baseline N66R speeds were 80-90 Mbps, max. The same settings on the AC66U were generating speeds ranging from 15% to up to 50% better (110-150), located in the same exact spot. I just assume the AC66U has better hardware, power, etc. When I upped the channel bandwidth to 80 Mhz (selected 20/40/80), the speed shot through the roof - sometimes 300-400 Mbps, especially on my 802.11AC capable devices - never seen that kind of bandwidth on wifi here. Even older machines, with only 802.11n, had 200Mbps pretty consistently.

Then, all my neighbors came home. And, as expected, the speeds started decreasing. Then out of the blue the signal went dead (no 5 Ghz). The router was alive, and no issue logging in on the 2.4Ghz. So, I've read up on DFS channels, so I'm aware the router will force the 5Ghz radio off if it detects radar, etc, on those bands - and the system was behaving like this was the case - but I wasn't on a DFS channel (I was on 149 here in the USA).

I was expecting a speed reduction during congested hours, but I was not expecting the Asus to simply turn off the 5Ghz band. Does anyone have any insight on this? I thought the 20/40/80 bandwidth selection allows the router to auto-decide the best bandwidth given the congestion in the spectrum - I didn't think it would just cut it off. I switched back to 20 MHz, and it appears stable, but that's really not ideal.
 

L&LD

Part of the Furniture
While not ideal for you as a user, it seems like it is the best you can expect for your WiFi environment as described.
 

Gnome10

New Around Here
While not ideal for you as a user, it seems like it is the best you can expect for your WiFi environment as described.
I understand that the router will back off, reduce bandwidth, to mitigate interference (not only for me, but my neighbors), and as already stated, I'm fine with the reduced speeds when everyone is home, but why did the 5 Ghz just cut out completely?
 

L&LD

Part of the Furniture
I think Channel 149 is a DFS Channel? How long did you wait to see if the 5GHz band came back? It could be up to 5 minutes is my understanding.
 

Gnome10

New Around Here
I think Channel 149 is a DFS Channel? How long did you wait to see if the 5GHz band came back? It could be up to 5 minutes is my understanding.
I honestly couldn't tell you. I was coincidentally setting up something else, and thought it was related (it wasn't) - I thought I messed something up. But, after repeated attempts, I'm pretty sure it was longer than 5 minutes. The 5Ghz signal was definitely not present, as even inSSider couldn't see it.

Really, 149 is DFS in the USA? I thought I've seen a bunch of charts saying otherwise, but maybe I was reading the wrong country. It would explain it, but the timing of increased neighbor interference would be odd coincidence.
 

Gnome10

New Around Here
Yes, But it might be your WIFI card that can't take that channel?
Works perfectly fine right now (during the day), on all devices I've used (which are more than 10). (WiFi) Bandwidth speeds are 300-400 Mbps right now. My guess is I will mysteriously lose the 5 Ghz later in the day, just like before.
 

DarnellG

Occasional Visitor
I'm getting something very similar when I use the upper 5Ghz channels. I've tested this with a RT-AX88U and RT-AC5300 independently and if I choose any upper channels 149-161 and run at 80Mhz the signal strength goes very low or gone completely. If I reduce it to 40Mhz the signal returns to the proper levels and I get about 250Mbit/sec throughput. Clients typically can connect but cannot transfer much of anything. What's weird is I'm in a fairly open wifi space with only my neighbor's AP using ch1 on the 2.4Ghz band and only occasionally do I see his very weak wifi signal (-80 to -90) on the upper 5Ghz channels. I have no issue running on [email protected] and get over 500Mbits -750Mbits using iperf on my desktop and samsung s10. I would really like to know whats going on with my routers that makes it act this way on those upper channels.
 

Gnome10

New Around Here
I'm getting something very similar when I use the upper 5Ghz channels.
Same, I've backed it off to 40Mhz bandwidth, and it's been rock solid. Someone maybe should contact Asus directly to ask if this is part of the protocol, or a bug.
 

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