I can confirm the same issue. I have a 6.9.2 server that had a basic license. I added several new drives and ended up in the same situation. No web access at all, etc. I could sign in at the console command line and was able to review the syslog. I found the entry from ethttpd referencing too many devices. I unplugged disks until I was under the limit for the Basic license then booted up again. Everything came up as expected. I was then able to upgrade my license, shutdown, re-attach my new disks, then boot normally again. I currently have version 2021.07.28.1824 on the My Servers plugin installed.