I've been using an apu2 as my home router/server via an MC220 media converter on a 1G fiber optic line for years without any problems. Now I've 'upgraded' to an apu6b4 in order to get rid of the MC220. I transferred the SSD (Debian bullseye) from the apu2 to the apu6, adapted the interface name for the SPF WAN port and everything was running great. Unfortunately, the apu6 freezes about once a day. The front LEDs get stuck and the whole system is completely unresponsive, nothing in syslog, nothing on serial. Latest BIOS. I replaced the PSU, didn't help either. CPU temp (k10temp-pci-00c3) around 65C just like on the apu2.
Has anyone else seen something like this? How can I find the reason?