I have a server installed on a NAS (Synology) and it’s running fine. I’m able to access the server and all my content from iOS and Apple TV App and when I start Plex directly from the Synology OS.
However, when I’m using my Mac, either Mac OS app or app.plex.tv I’m unable to access the server UNLESS I’m using av VPN service (i.e. browsing through another IP than the one provided by my ISP).
I seem to have missed that part of your setup… how are you using an external IP to access the local PMS on your Syno from your Mac? I’m a bit lost… is the NAS on a different network but the other clients and the Mac are on the same network – however only the Mac failing to connect to your server?!
Accessing the server works fine when I’m on an app (like in iOS or TV OS), I’m guessing because they’re on the same local network as the Synology.
However, I run into trouble when I try to access the server in a browser (i.e. via app.plex.tv). Could this be because I’m trying to access it from outside of my local network?
Anyway, the problem seems to be with IP addresses I receive from my ISP. I tried connecting to the server from my office (where I have the same ISP as at home) and it doesn’t work from there either.