ROG B850-G Gaming Wifi Motherboard - weird issues

I've been waiting for the B850-G Gaming Wifi to finally arrive at my usual supplier, so when it did I immediately went and bought it and ported my system over to it (and did a fresh install).

However, now that my system is being brought up to speed, I'm beginning to see a couple of strange issues.

Every now and then, the Wifi signal dies completely, with Windows no longer every recognising that a wifi device is present. And when it does, my case fans all stop spinning at the same time. If I do a shutdown or reboot, all the fans in the system will keep spinning even after the system is powered off, and in the case of doing a reboot, will system not boot until I do a hard reset via the power button.

I'm using Fan Control to manage the fans in my case (CPU cooler, GPU, & case fans)

I'm using BIOS version 1066 dated 2025/06/27. While I suppose I could try a BIOS flashback, I thought I'd try asking here first.