The "Log Settings" configuration page does not allow setting up a remote syslog server with a custom port.
While the current implementation works for the default port 541 it does not work for any other ports. The user input is checked and rejected if the IP-address of the remote server contains any port.
This makes it impossible for e.g. using a syslog server running in a docker container which cannot exposed the default port 541 for various reasons.
This includes any other setups that do not use the default port either.
I believe we cannot change this at the moment, because sysklogd which we are using does not allow changing the port.
This has been requested before and we probably need to replace the logging daemon with something more modern like rsyslogd first. However, we are lacking development time for this at the moment. Please get in touch if you can and want to sponsor this.