UrBackup Server 2.5.33 starts, then becomes unreachable after a minute

Hi,

i have UrBackup running on a QNAP TS-673A. I´m using the qpkg by Stephane that is linked on the UrBackup website.
It was working flawless for some weeks. After i rebooted the NAS, the trouble started.
When i start UrBackup manually, the website is available for a minute or so and then becomes unreachable. The error in the browser is ERR_CONNECTION_REFUSED.
In the logfile, there are a lot of errors. When i delete all files in /share/ZFS1_DATA/.qpkg/QUrBackup/var/urbackup and start from scratch, everything works again until i stop UrBackup manually or the NAS is rebooted. It´s always the same, happend a few times already.
Here´s the log, can anybody assist?
urbackup.log (33.1 KB)

Nevermind.
It works in a full VM with NFS share.