After doing a omv-update and reboot, I tried to access the web gui and all I got was a blue background without the login form.
I ran omv-firstaid and tried all the options to see if it would fix the problem to no avail.
However, after running the first option it gives the following error: After that I lost access to the server remotely, and I haven't been able to restore it since. Since port 2812 is used by monit, running export LANG=C; monit -B summary 2>&1 gives: I tried to run omv-mkconf monit and systemctl restart monit which seems to fix monit, but I still don't have remote access. If I do configure network interface with omv-firstaid, I get the same error above and I'm back to square one.
After restarting the whole network and the server several times, the monit problem went away. However, I still can't properly access the webgui, since it doesn't display the login form.