Are you running the latest firmware, version 3.0.0.4.386.48631? If you are, from my experience, that firmware version is quite buggy and I've experienced a similar thing where my router would reboot with those kernel messages. I had to switch to a Merlin firmware for now to get my router stable...
My AX88U has been stable ever since I bought it until I installed this firmware. The router would just stop, kick all wireless clients and reset itself. And then the system log showed a bunch of Kernel Console errors with my Google devices. I switched over to the latest Merlin firmware and...