Thanks for the Forum!
Is the web interface no longer installed in the new version?
Has the file system of version 5.1 changed on the data partition?
I can no longer access the data partition by using "Paragon ExtFS for Windows".
The web interface is broken in 5.1. I didn't see it was. I've fixed it for 5.2 coming soon.
The data partition didn't changed in 5.1. Still an ext4.