@RogersIan Looks like the power levels for U-NII-1 and U-NII_3 are back to normal. I ran some tests using 80MHz channels on the 5Ghz band and noticed while switching channels, the router becomes unstable with IP connections on wired and wireless. I...
Seems like U-NII-1 and U-NII-3 power levels on the 5Ghz band are back to normal. Also, toggling the channels on 5Ghz does not turn the radio off/on, anymore. I will do some more testing for consistency.
Don't rule out your modem/router yet. Check for speed/duplex mismatches between both, in bridge and gateway mode. There was a old bug with router ports and speed/duplex. It may have reared it's ugly head again.