My wife got me a Commodore 64 Ultimate for my birthday and it's nifty, but I started having a problem with it where, after running the device for a bit and not interacting with it, the C64U Menu would stop coming up when hitting the multifunction switch or the C+RESTORE keys. The only fix was to reboot the whole thing. Strangely, when this would happen, the video stream would keep working from the device but the web service would flake out too. Eventually even after rebooting I would have an issue with the web service coming back up.

Well, today someone posted on Reddit that they were having the same issue, but they identified that it seemed to be related to their HDMI cable. So... I unplugged the HDMI cable from the back of the C64U and it's been 20+ minutes now and everything is still working great! I think there must be some sort of problem with HDMI in the 3.14 firmware...