My friends cant see my server.

[DevTheGuy]

So I am trying to play with my friends I turn on upnp and I am on port 2302 and then I start up the server but my friend doesn't see the server and I check my router settings and everything is okay there oh and also turning on upnp and starting the server on port 2302 used to work in the past but then one day it stopped working. Does anyone have the solution?