Use this to check the ports of the server - http://canyouseeme.org/. Until you see it pass. If it fails put the server in the DMZ of the router to see if it passes then. If it fails then, the issue is the server firewall or could be AV as some AV have firewalls in them now. If it passes you need to look at the rules, upnp, firewall settings in the router. Edit - I should have put in it only works when you have the server running when you test.
There is also a bug when you are on the same intranet you cannot see the server. I have this as I have 2 different vlans and I cannot see my own server.
Make sure you do not leave it in DMZ though as it is wide open while you are testing.