Robot CIP Safety Comm Timing out

Hi.

I'm wondering if anyone has happened to you that the robot is communicating properly with the PLC, using standard and safety over Ethernet IP, but suddenly stops communicating with the PLC for about 5 seconds and then it starts communicating again?

We have changed wiring, PLC ethernet cards, PLC processors.
Setting the varible ETH_FLTR 4 to 44818 worked for the r30ib plus but the r30ia controllers are still timing out every 30 or 40 minutes.

The funny thing is that this ethernet network is shared with other PLC with the same mix of old and new controllers but that PLC has no communication issues.

Even when isolated from the other half of the network we are getting timeouts.

Any advices?

Thanks!