Omron NX connection problem

Omron NX connection problem

Hello,
I have a problem connecting to PLC NX102. Often after starting the computer, the connection to the PLC does not work properly and I have to restart the computer again.
Diagnosis Viewer displays two errors:
- Receiving EthernetIP Header failed.
- Error reading variables. CIP request error. Error code = -2
What could be the problem?

zenon  Software Platform 12

Build version: 324144