I posted this problem a few days ago and I have just replicated it again and it appears to be caused by a mangle rule added which when rebooted causes the system terminal to crash when it loads and it’s impossible to connect by network or even on the machine itself as you cannot login. The rule I added was a http conection mark which was not marking traffic so I rebooted to see if it became effective. After rebooting problem!
Just done some more tests and it is not the configuration change as I have a config backup which I created on the 2.9 b19 system and I had saved the configuration and rebooted and it was OK but then I made the above change and after reboot problem! Anyway I did a new install loading the config that worked and I got the problem still when the system had booted
The only error message I can obtain is only what I can see on screen when holding ctr alt del to reboot after the terminal fails to login it waits for a long time and then gives this message:
rebooting
stopping services
failed to stop console: std failure timeout (13)