I have a Minecraft server. I have run Minecraft servers for years, and it even used to work on an Xfinity router. I bring my server over to my friends house, basically change all of the hardware, reset it, do everything to the server to make it fresh, and I open port 25565 in port forwarding using TCP/UDP. It doesn't connect. The problem is that when I restart the router, it allows the server to be accessed for approx. 15 seconds, then it closes the port, and the only way for it to re-open is for the router to be restarted. Any help?