I had the same problem: installing with:
sudo wget -O - https://raw.githubusercontent.com/OpenMediaVault-Plugin-Developers/installScript/master/install | sudo bash
on a Raspberry-Pi OS Lite
I checked my router and the IP of the RPI seemed to not have changed.
No matter if WIFI or LAN i could not ssh into it after OMV installation.
ssh: connect to host 10.0.0.xxx port 22: No route to host (every time)
Then after 5 reinstalling attempts I restarted my router....
Then I connected the PI via LAN to the router and finally the IP had changed.
I think it was changed all the time but my weird A1 router did not update and showed me the old IP.
Now I can finally log into OMV using the web browser.
Because I was so mad that I did not work at first and I saw that you guys also had such a struggle I signed in to this forum to post the FIX.
my MSc / Robotics engineering brain took 6 hours to try the "have you tried turning it on and off again" method.