Twincat and PLC Port Was Disabled

yesterday found that the cp6920 beckhoff ipc ethercat port was automatically disabled and can not communicate with beckhoff plc, the setting for port setting are all aumomatic. what reason to cause this error happened. and once we restart the plc then ok, after some time still happened.

I would suspect a program or service in Windows is doing this. Insure you have no firewall set and investigate any security programs you have installed, like McAfee or Norton.