Hi there, I'm not exactly sure what logs and stuff are needed to properly diagnose this, but basically setting the 5 GHz radio (radio0) to auto channel selection (channel width doesn't seem to play a role) causes the radio to dissociate and not come back online, even after waiting 10+ minutes. Both radios are broadcasting the same network name.
Auto does not mean auto, but first legally usable channel. And if that channel is a DFS channel, you will have throuble in that router.
Try to configure a specific channel, and watch the logs to see why it does not come up.
Thanks for your help. Is there a way to use automatic (dynamic) channel selection on both the 2.4 and 5 GHz radios?
AFAIK, OpenWrt does not support automatic channel selection, neither on 2.4GHz or 5GHz; see the definition of "auto" in "channel" at https://openwrt.org/docs/guide-user/network/wifi/basic#common_options.