My recent Unraid server build failed the same as this, I then wiped the USB and installed from scratch and then re-installed all apps, shares and VM was there still and within 15 minutes I was back up running.
I purchased an upgrade from plus to pro due to a partial error on my behalf, added the extra 8 drives and restarted and now I can ssh, ping the server but I can't access the Web GUI again.
I have changed the port from 80 to 80008 but no joy still, attached the diagnostic zip to see if you folks can assist. I did add the device as a static IP from the router, the router alos shows the right IP, I can ping the UP and the DNS name.
Look forward to some suggestions. There maybe a bigger back story which may help but a long write up.....
proliant-diagnostics-20210326-1852.zip