Plex is accessible even with closed ports

Plex Media Server
1

Server Version#: 1.24.1.4931
Player Version#: Plex Media Player 4.29.2

Hello. I noticed really weird behaviour. Plex is accessible without actually opening ports. The only thing is that my ISP set their modem (inside my house) to Bridge mode so no ports will be blocked by their modem. Now, when i port forward port to plex, it’s accessible on canyouseeme.org , when i disable port forwarding, canyouseeme.org can’t reach that port but plex
(in the plex app, not web app) is still accessible remotely from outside world. Only if my ISP set the modem to normal mode, the plex become inaccessible to the outside.

So there’s something else what plays the role in remote control of plex server?

2

There is a relay to provide access even when port are closed but limited to 2 or 3 mbps. You can disable relay in the network settings if you want.

3

I understand. So Plex has proxy servers which proxys the data from my server, through their servers to the remote user. I also found the limitations that are 1 Mbps / free user and 2 Mbps / paid user. It wouldn’t bother me cause i use plex mostly on flac music which is (in CD quality) around that 1 Mbps. But when i have let’s say LP quality, with 5 Mbps bitrate, what will plex do? It will convert it to AAC low quality or somehow convert it to that limit 1 Mbps?

And the second and main question. When plex have proxy servers, why am i not able to send data through that when my ISP set the modem to normal mode (so it’s blocking all ports)?

4

Plex Relay is an outbound connection.

  1. Your server has an open connection (outbound) to Plex.tv which is sustained when Relay is active.

  2. The player makes the request.

  3. Plex.tv sees there is no direct port

  4. Plex.tv sees Relay is active

  5. Plex.tv sends the play request through the Relay connection.

  6. PMS sends back the data (1 or 2 Mbps) to Plex.tv, which then sends to the player.

The play request traffic