Now I'm in an endless reboot loop. No error messges. Took the wifi down for a while and no reboots. Then brought the wifi up and as soon as it was done connecting, instant reboot and back to the loop. Then I took the wifi down again and connected via ethernet. No reboots so far. So seems like it has to be either a hardware issue with the radio or related, a wifi driver issue, or some crazy wireless glitching over here.

Got a reboot after 5 hours with the wifi down so maybe not.

So did you build a custom firmware yet? If that doesn't help then I'd start suspecting a hardware issue.