How can I connect a PLC if it is not found by the Scan Network in Codesys 3?

If your PC has multiple gateways ,  scanning the networks may not work to connect your PLC.  In this case, please type the IP address of the PLC, if it is known, and it ENTER. The Led on the PLC icon should turn to GREEN.  if not,  please double check the IP address .  If you still experience the connection issue, please try to ping the PLC.  If pinging is successful, please update the OS and Codesys runtime in XC/XV.