Indirect connect and no external connection

[MetaMeu]

Hi,
I'm sorry for the, probably, noob questions.
I have this problem: I use my TerraMaster F2-210 as a Plex Media Server. If I connect to plex via browser (192.168. etc) it's all good. If I connect via the app, both on pc and Fire Stick inside my home network, Plex says that the connection is indirect. Why? How can I solve the problem?

The other issue is that the "external connection" isn't working. I'm not able to realize if the problems can be solved inside the TNAS or in the modem setting page.

Thank you!

[TMroy]

For this issue, you better ask for help from plex support.

[unixtall]

Did you opened the ports in your router?

[MetaMeu]

Did you opened the ports in your router?

I think yes. The ipaddress of the TNAS is 192.168.1.150. I opened the port 32400 TCP.
Do I need to open some other ports?

[unixtall]

Check this in your plex settings.

Check the picture.