Remote Access not working since moving over from one ISP to another (cable provider to fttp)

Plex Media Server Remote Access
1

Server Version#:PlexMediaServer-1.31.3.6819
Player Version#:1.66.1.3632-4d9c7716 (plex for windows)

Hi,
so a bit of an odd one. I’ve been with a cable ISP provider for many years. I always operated my cable modem in modem only mode and had my own firewall (pfsense 6.2) and wifi setup. I had created port forwarding rules in my firewall/router for my plex media server (which is running on a local synology server under DSM 7. All this was working fine and i had no remote access issues . However yesterday I moved over to a new provider (Vodafone on the Openreach network here in the UK). Basically this is FTTP (fibre to the premises) and uses PPPoE for link authentication. In this scenario my router plugs directly into the fibre/network unit installed and there is no intervening device between me and the network and no double NAT as a result. All working fine and got PPPoE working and internet up and running. This provider has a dynamic IP so if I reboot my router the IP can change. Also they use a specific VLAN tag for my traffic. I assume this is so it can be routed correctly on the openreach network (there are many different providers running over this infrastructure).

So that’s the setup. However I noticed that externally or in fact via any web UI i could no longer connect to Plex… I checked my firewall. All as before. I check synology firewall. I have a rule in place to allow anything within my local LAN to talk to the synology on any port so that should be fine as before. I’ve got other programs using UnPnP via the firewall and they are working fine. However within the windows client i have on my local workstation (which still works) when i check the remote config Private IP and Public IP just have a red X next to them… So I’m struggling a bit to understand what may be the culprit. I tried changing the external port from 32400 to 52400 in case my ISP was blocking this well known port (changed the firewall rules accordingly). Still the issue is the same and Plex is not picking up the local and remote IPs.

I used this guide to double check my setup was ok and I’m broadly identical bar the different external port

Any ideas on where to look for clues as to why?

2

Issue resolved. I decided to look through the logs myself. Quickly worked out that I had not updated the primary DNS resolvers for the synology and it was still using my old ISP DNS. Once this was amended everything began to work as expected…one to remember for the future.

L