Network port number changes back to default after restart

Hi folks,

I use a port number other than the default 9000 or 9002 to access LMS 7.9.1-168 on my Synology DS118, either thru web interface or app on my phone. For some reason I lost connection and wasn't able to connect again. After some digging I found out that the port number I set, which is different from the default 9002 on Synology NAS, was set back to 9002. This happens either after an update (which restarts LMS) or just a manual restart.

Is this a bug or is this behavior intended? Either way, how can this be prevented?

Thanks in advance for your support!

Regards,
Hans.