Hey there! I’ve been running a Plex Media server on my old pc since about febuary, but have always had the issue that it will always fail remote connection, If it does go green, only for a few seconds then back to not working.
There’s also a guide with some more details on how to troubleshoot remote access issues. In order for others to help, you’ll need to share the individual output of those steps, e.g. starting with can you actually see/access your router’s forwarded public port from outside your home network (e.g. using a service like canyouseeme.org)?
The test always shows green at first before the test actually starts. Do not interpret this as “it WAS working for a second!” That is almost certainly NOT the case. The built-in test is misleading and Plex should fix it.
Use a remote port checking tool instead of the built-in tool.