No GUI after Upgrade from MR4 to MR5

Hi. I really hope someone can help me with my issue.

I am using Sophos XG Home Edition on Intel Hardware. Worked perfect until las update. After I updated from version MR4 to MR5 I have no access to the GUI anymore. The error is: 

This site can’t be reached

192.168.32.254 refused to connect.

Look like that only the GUI is not working. All other Firewall settings look good. VPN, WEB Protection. SSH is working. I have full access to the console.

I tried several things to resolve the issue. This is what I already tried:

1. Use SFLOader to load old Image (MR4). Still no GUI with old image.
2. Thru console, I restored factory defaults. After this, the GUI is available again. However, with an empty firewall configuration (as expected). When I restore my Backup, I have the same problem again. No GUI.
3. After loading factory defaults again, I updated to MR6. Still working but with an empty configuration. If I restore my backup, I have the same issue again. No GUI.
4. I also tried Backups that are 14 days old.

Does anyone have some Idea, what I can try? Maybe something on the console.

Any help is much appreciated.

Thanks.