Plex Media Server not found, though successfully installed and running on Sinology DS415+

Hello!

I am running Plex (1.2.2.2857-d34b464) on a Synology DS415+ with DSM 6.0.2-8451 Update 2. The network also contains a Cisco SG112 gigabit switch, to which the router, the NAS and my MacBook connect. The following problems occurred on an Apple MacBook Pro 13” running El Capitan, browsers tested were either Safari or Firefox – MacOS and all browsers were latest versions.

Though Plex appears to be running when checking on the DSM6 GUI, it is not possible to connect to the Plex Media Server when clicking on the respective link. So far I’ve double checked all necessary firewall exceptions, port forwardings, etc. Everything is fine, port 32400 and the other relevant Plex ports are all allowed. Both on the router and DS415+ internal firewall.

I also tried uninstalling/ installing several times with no positive effect.

Any recommendations are highly appreciated!
Thanks for your support!