Micrologix 1400 loses coms intermittently

Hi guys
I have an intermittent issue with a micrologix 1400 which connects to a pvp 700 via Ethernet loses coms
I’ve been told by our shift engineers that our liquid system runs ok for weeks and then loses coms ? The only way they get it working again is unplug the Ethernet from the plcand plug back in and then it works ok until the next time ?
No fault light , or codes??
Can we trap the fault or is there anything Pacific to look for ?
Thanks stu

Is there an Ethernet switch involved, or is it a point to point cable?

If there is a switch, I'd try swapping it. I've seen many such intermittent comm failures over the years caused by a failing switch.

Yeah there is a switch I will try that thanks

Is this a new problem? Definitely change the switch as stu said, and maybe the cables. If the Ethernet cables run along something with high voltage or high frequency, then the Ethernet cables should be double shielded (foil and braided).