Two PC copies but only one PC can connect at a time

This is a common issue with routers that has trouble sending the right data packets to the right computer when both computers are connected to the same server.

Most often this can be fixed by reconfiguring the router.

The following steps often help:

1 Log into your modem / router
2 Turn OFF UPNP.
3 Turn off PC UPnP Service:
4 Press: Windows-button a window should pop up. Write: “services.msc” (without the “) then press enter.
5 In the list of services, scroll down to “UPnP Device Host”, click it and press “Stop service”. Now do the same thing but with the service “SSDP Discovery”.
6 Exit the window and go to control panel-> Network and Internet-> Network and Sharing Centre-> Change advanced sharing settings (to the left)-> Under “network discovery” select to turn off network discovery
7 Save your changes

Also, updating the router firmware can help.