RT-AX56U leaves DFS channels without reporting any radar events

[Volt]

RT-AX56U automatically switches from a DFS channel (which was selected either manually or automatically) to a non-DFS one without any indication of the radar detection event and remains on this channel forever until the router restarts. It seems to me that this behavior is not correct, and I can't figure out what triggers it. My initial idea was that some client was the cause and I tried to disconnect devices one by one from the network, but the problem remained. I understand that theoretically this switch may be triggered by some interference, but shouldn't there be a log message about it? Should not the router either report a radar event or remain on the DFS channel?

I would appreciate any help.

UPDATE: I finally found the reason for this behavior, and it seems fantastic. As soon as I switch to the "WDS" tab in the "Professional" settings, the router switches to a non-DFS channel. Can someone check if his router is doing the same (first make sure that 5GHz band is selected on the "General" tab; otherwise, this cannot be reproduced)? Is this normal behavior?

 

[JagoUK]

RT-AX56U automatically switches from a DFS channel (which was selected either manually or automatically) to a non-DFS one without any indication of the radar detection event and remains on this channel forever until the router restarts. It seems to me that this behavior is not correct, and I can't figure out what triggers it. My initial idea was that some client was the cause and I tried to disconnect devices one by one from the network, but the problem remained. I understand that theoretically this switch may be triggered by some interference, but shouldn't there be a log message about it? Should not the router either report a radar event or remain on the DFS channel?

I would appreciate any help.

UPDATE: I finally found the reason for this behavior, and it seems fantastic. As soon as I switch to the "WDS" tab in the "Professional" settings, the router switches to a non-DFS channel. Can someone check if his router is doing the same (first make sure that 5GHz band is selected on the "General" tab; otherwise, this cannot be reproduced)? Is this normal behavior?

IIRC WDS does give a warning before enabling.

However, I would point out that radar pings causing DFS to shut down a channel wouldn't always show up in my system log on my XT8.

What you can try doing is turning the router off and on again and look in the wireless log for a DFS event.

See my review in my sig for more details.

 

[brummygit]

I've just found this thread as I'm suffering the same 5Ghz channel hopping on my RT-AX56Us. I don't use WDS, but either AP mode or AiMesh - they do it in both modes.

Did you get anywhere towards solving the problem?

What firmware were you having the problem on?

 

[erick_e]

UPDATE: I finally found the reason for this behavior, and it seems fantastic. As soon as I switch to the "WDS" tab in the "Professional" settings, the router switches to a non-DFS channel. Can someone check if his router is doing the same (first make sure that 5GHz band is selected on the "General" tab; otherwise, this cannot be reproduced)? Is this normal behavior?

Out of sheer curiosity I tried this with my GT-AX11000, and as soon as I clicked the WDS tab my 5GHz-2 changed channels from 112 to 149.

 

[Volt]

I've just found this thread as I'm suffering the same 5Ghz channel hopping on my RT-AX56Us. I don't use WDS, but either AP mode or AiMesh - they do it in both modes.

Did you get anywhere towards solving the problem?

What firmware were you having the problem on?

Your RT-AX56U can switch channels for objective reasons, like because of radar detection events or busy channels. This is normal behavior.

In my case, I've noticed this abnormality because I had no other 5Ghz networks in vicinity and no radar detection events in the log. If you are sure that this is your case, then restart the router using the power button (it should automatically select channel 100 if you are in Europe) and then just do not open the "WDS" tab in the "Professional" settings. By following these steps, I prevented the channel hopping (now AX56U stays on channel 100 for weeks).

From the usability point of view, I think that ASUS should somehow inform the user that the router will automatically select non-DFS channels when opening the "WDS" tab.

 

[brummygit]

Your RT-AX56U can switch channels for objective reasons, like because of radar detection events or busy channels. This is normal behavior.

In my case, I've noticed this abnormality because I had no other 5Ghz networks in vicinity and no radar detection events in the log. If you are sure that this is your case, then restart the router using the power button (it should automatically select channel 100 if you are in Europe) and then just do not open the "WDS" tab in the "Professional" settings. By following these steps, I prevented the channel hopping (now AX56U stays on channel 100 for weeks).

From the usability point of view, I think that ASUS should somehow inform the user that the router will automatically select non-DFS channels when opening the "WDS" tab.

In my case I don't normally open up the WDS tab so I don't think this is my problem, but I do think there is something possibly environmental near one particular AX56U which switches more frequently (maybe once per 24 hours) or maybe a false positive radar hit. The issue is that it drops onto channels 36-48 which are heavily occupied by my neighbours such that a number of my outlying devices can't successfully use the network. This seems to have been reported more on RT-AX56Us than other routers from my searching. My RT-AC68U in the same location stays on its configured channel.

Even though DFS shows the channels cleared for use, once I've been bumped off my configured channel my connection never returns. In earlier firmware versions I saw the 5Ghz radio bouncing around different channels every few seconds (including DFS channels), more recently (since 386_41700??) it seems to stick to the channel it first lands on. In either case I discover the problem when devices on my network are losing connections of access is very slow.

 

[Volt]

The issue is that it drops onto channels 36-48 which are heavily occupied by my neighbours such that a number of my outlying devices can't successfully use the network. This seems to have been reported more on RT-AX56Us than other routers from my searching. My RT-AC68U in the same location stays on its configured channel.

Even though DFS shows the channels cleared for use, once I've been bumped off my configured channel my connection never returns. In earlier firmware versions I saw the 5Ghz radio bouncing around different channels every few seconds (including DFS channels), more recently (since 386_41700??) it seems to stick to the channel it first lands on. In either case I discover the problem when devices on my network are losing connections of access is very slow.

I saw the same behavior when my router switched to non-DFS channel after me visiting the WDS tab - AX56 stayed on channel 36 for days and never returned to any of the DFS channels. Unfortunately, looks like not much can be done about it. Does the log provide information on why your router switched to non-DFS?

 

[brummygit]

No, I've once seen a RADAR event, but generally not.

I have a case open with Asus who have asked for more diagnostics. I'm waiting for an event where I get the entire log from reboot to send them everything they've asked for this time.

 

[crashburn162]

I've tried this on AX92u doesn't trigger hidden ssid is channel 100 and normal is 52.

 

[brummygit]

I supplied the information Asus requested from me and whilst I'm waiting I tried a couple of things:

• Running my RT-AX56U in AP mode (I get the issues as an AiMesh node or running as an AP) with firmware 3.0.0.4.384_10290 I see the same issues
• I swapped to my spare RT-AC68U with firmware 9.0.0.4.386_41994 and it's remained on channel 100 for days without a problem

 

[brummygit]

So I have a conclusion of sorts to my issues. After sending diagnostics to Asus and a few email exchanges they told me to contact my seller to RMA for repair/refund. Amazon have been great and issued refunds against both of my RT-AX56Us so I have sent them back and will be ordering a different router model - I'm thinking of a pair of RT-AX86Us.

Interestingly mine were hardware version 1.0 with serial numbers 228 and 229 so I suspect they were from the first manufacturing batch.

 

[Zetto]

This crap is happening with my newly acquired AX55, just clicked on WDS tab in wireless and 5ghz channel dropped from 60 to 36 (didn't make or apply any changes). I guess I should return the router... I do not accept that that simply clicking on some setting (which could be accidental) without making any changes will cause issues for router setup this way, this is NOT normal and can't be tolerated.