I had no issues when Upgrading from 25.7.11 -> 26.1 -> 26.1_4 however after upgrading today to 26.1.1, I had no WAN ipv4 connection.
A software restart via GUI didn't resolve, in fact after the restart many services were not running as could be seen in the Dashboard widget.
I then tried to physically power off my machine (Protectli 2410) and noticed it was extremely hot and it didn't respond to my pressing the power on/off button.
After I pulled the power cable and reinserted it, the system rebooted and everything came up OK including WAN etc. and the temperature went back down to normal levels
Very strange, I've never experienced that before.