After applying CU 170, the internet connection works fine for a while (not sure if minutes or hours yet) but then fails. On the main page, under Internet, the Hostname changes from the ISP hostname to IPFire’s internal hostname and no internet connection works, even the IPFire box can’t seem to see it. Rebooting IPFire restores normal function temporarily.
Edit: Confirmed that I have an AX88179 Gigabit Ethernet (ax88179_178a) USB3-ethernet adapter from the other post linked as the solution
It’s not that bad, you save on your laptop or desktop the backup of the configuration (it is automatically created and you can download it from the WUI), reisntall from scratch and restore. It’s the best way, believe me.