Unable to do image backups over internet

I set up urbackup in a docker on DSM, I did a full backup whilst on the local network, I then enabled internet mode and made sure the boxes to do file and image backups over the internet were ticked.

The machine was then moved to a remote location and the ports were forwarded, file backup still works fine but when trying to do system image backup, it backs up the sysvol and then stops, on the client screen it now just shows disabled.

What am I missing here?

Log shows:

22/06/20 20:28 INFO Starting unscheduled full image backup of volume “SYSVOL”…
22/06/20 20:31 INFO Transferred 296.477 MB - Average speed: 14.1735 MBit/s
22/06/20 20:31 INFO (Before compression: 312.775 MB ratio: 1.05497)
22/06/20 20:31 DEBUG Script does not exist urbackup/post_full_imagebackup

Make sure “Do image backups over the internet” is enabled in the settings, it’s disabled by default.

Literally the second line down in my initial post.