Remote access not working on smart TVs outside network

Plex Media Server Remote Access
1

Remote access is showing me that my server is not available outside my network. However, I can access it via the phone application on 4G/LTE, friends have reported being able to cast from their mobile devices to their TV on their own networks but NOT being able to access my server from the smart TV apps on the same network. Anyone able to advise why this might be?

Server Version#: 1.18.8.2527
Player Version#:

2

Cause Plex is getting worse every day?.. I’m trying to set mine up on a VPS, but when anyone tries to watch any media it says the server IS OFFLINE when it’s really not, I dont suggest buying a plex pass until you really understand plex

3

What brand of Phone and brand of TV and model?