Plex under firewall & dual nat

Plex Media Server NAS & Devices
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Server Version#:1.22.0.4163
Player Version#:latest
Dear all I am facing some strange behaviors with the plex and I would like to gave your point of view.
Under a firewall Plex is working fine but as soon as the plex if facing double NAT , only the plex under Windows is working. I tryed with Synology and truenas but not working under doublenat.
No errors are notified within the packet capture or firewall logs. is there any limitations?
nowdays in france we ar obliged to use the ISP modem that are not accepting bridge configuration so if we really want security we are obliged to put a firewall below the isp modem hence the dual nat configuration. Actually for me only plex on windows is supporting this network configuration. did i ommit something ? what would you suggest to make it work with a truenas or synology?

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With multiple Plex servers in the same network you usually need to establish a manual port forward for each individual PMS to avoid them from „colliding“ when attempting to establish their connection to the outside world via UPnP. With a double NAT setup that’s possible too but trickier… you’ll need the port forwarding on both network components:

  • the modem forwarding requests to a defined public port to the router @ the public port used on the router
  • the router forwarding requests to its defined public port to the PMS @ port 32400
  • the public port inside Plex should refer to the one configured on the modem

For that to happen you’ll need some level of access to the modem

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Thank you for your feedback,
I am using port forwarding from the isp modem for the tcp 32400 and working fine with Plex for windows with simple nat overload on the inner firewall.
However for the Plex on Synology or Truenas is not working the same.
I will try to forward both outbound and inbound based on the same tcp ports on the inner firewall.
The objective is to use Plex on smaller device.
Will give you feedback this weekend.
Thanks again

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They’ll need individual ports. Otherwise those external requests cannot be distinguished and associated to one of the individual servers.

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