Has anybody experienced this random issue with their MR34's where the 5Ghz radio just suddenly stops broadcasting and the only way to get it back is to reboot the AP? We are running 26.6.1 and using 40Mhz channel width.
26.8.2 is the stable release for the MR34. I would recommend upgrading to that and see if it resolves the issue. In dashboard the current stable is 27.7.1, but it will run the MR34 at it's max which is 26.8.2.
You might want to also shoot a case over to Support so they can look at the logs and see if something more obvious is occurring.
We have opened many cases about this issue. I was also told that the MR34's are able to upgrade to newer software but they will not use any of the additional features as they are considered EOL and could cause issues with them. One support person suggested downgrading them to a lower version. Thoughts?
I've seen cases in which downgrading to older 25.x releases helps with stability on the older AP's. It's often case by case based on config and usage.
The last case I see on this opened by you was Dec 2020. Perhaps open a new case online and request a downgrade to 25.14 to test stability. You could have Support downgrade just a single AP (or however many you want) to the older release so you can contain the testing to an area before downgrading all AP's.