5 GHz Channel State Does Not Reflect Configuration

Hello All,

First time post so I'll try to keep it short and sweet.

I have two routers, both WRT3200ACM running OpenWrt 18.06.2 acting as a master and repeater. They're bridged via their 5 GHz radios and I have no issues with the basic setup. I've tried to configure them both to use mid-band channels (like 60, 64, etc) to avoid collisions with other networks near by. At first the configuration works and I can verify with both OpenWRT and linssid that it's using that channel, but within an hour or so the router(s) invariably switch to either a high or a low channel that has a lot of overlap. I'm fairly baffled by this and am not sure how to trouble shoot other than a firmware update (which I'm holding off for now).

Can anyone advise on how to proceed?

I had a similar issue on a higher channel.

Dropping the maximum transmit power seemed to resolve it.

You're probably running into issues with DFS, when using DFS channels, the router first must listen to the ether for 60s, looking out for radar signals, before using the channel. If DFS events are noticed later at runtime, the router must immediately vacate the used channel and move elsewhere to a channel without radar interference. Your configuration is (must be) ignored in those case, as the (weather, flight security, miltary-) radar installations have absolute precedence over your WLAN (which could disrupt radar operations for well over 100km).

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In my case, DFS channels weren't being used.

The channels you listed in your OP are DFS channels.
Given your explanation of the routers suddenly switching to either a higher or lower channel, it's a pretty safe bet DFS is at play.

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I'm not the OP.

Whoops! :upside_down_face: my apologies

No worries.

Good graphic for the OP if located in North America.

Other locations -

From what I've read of DFS, and I could be wrong about this but I read it just the other day on wikipedia, if you have a channel set manually and the router encounters radar, weather interference then it is suppose to power down the radio. It is only suppose to switch channels if you are set to AUTO and also happen to be on a DFS channel when the issue happens. OP said he manually chose his channel.

Thanks guys. I've just been taking in the responses until I felt like I had meaningful feedback. You've more than answered my question. I am in North America (for the one that asked) and it seems like I'm going to have to find some other means than channel isolation to solve my connectivity issues.

This puzzles me as well, but I think it's certainly DFS one way or another that's the culprit here.

It could very well be, and It wouldn't be the first time something behaved in a way that it was not suppose to, if this is indeed what's happening. I hope you get it sorted out.

Do a 5GHz scan in 'Channel Analysis' under Status menu. Is it busy on either side but empty in the middle? Very good clue that DFS is in action for everyone at your location.