I have 3CX V12 SP6.1. The router is a DLink DIR-850L. 3CX works perfectly fine on one computer running Windows Server 2008 R2. But I need to move it to a newer computer running Windows Server 2012. However, when I point the router (UDP 5060) to the newer computer, that has the exact same 3CX conjuration on it, it periodically gives external incoming calls a busy signal or a partial (starts 5 seconds in) greeting. Redialing the call can result in it working. The 3CX logs and Wireshark do not give any revealing information on this. The server computer is not set to sleep in any way. Note that no other server application is running on that computer - nor is anyone using it directly. Is there something about Windows Server 2012 that I need to set to allow 3CX to get full and immediate attention? What else might be wrong?