Troubleshooting possible Ethernet/IP problems

I have recently added a ControlLogix 1756-L72 5570 to our industrial network and brought a number of tags into our existing ignition project. There is already another 1756-L72 and a CompactLogix 1769-L33ER that have been happily running for the last few years. The old controllers are running on firmware 20.13, while the new one is 21.11.

The tags on the new controller are updating for about 5 seconds, then hanging for a few seconds, before finally updating to their current values. The happens continuously. Simultaneously, the tags from the older controllers are updating just fine. This leads me to believe it is either a network problem with, or an ignition issue (I separately am seeking help on their forum)

I am the only controls guy here, so I'm looking for some help troubleshooting what might be the cause. My new setup is two 1734-AENTR racks connected to a 1756-EN2TR in the controllogix chassis. The second port of the EN2TR connects to a 9300-ENA NAT device. A cable (Helukat 250s, twisted pair shielded) runs 220' from the NAT to NEXTRON unmanaged switch to tie into the network.

The only indication that something might be wrong is a small number of FCS errors and MAC receive errors on on EN2TR port. I have attached screenshots of the diagnostic pages. Would these errors be enough to cause such a delay? Or is this normal and should I instead invest my time in problems with ignition?

Thank you in advance for any help.

The only "normal" number of FCS and alignment errors is zero. What you're seeing is plenty to kill an I/O connection... but maybe once or twice.

I would focus on the v21 firmware compatibility with the Ignition drivers you are using. Rockwell made a significant change to the security of firmware in v21 and also tightened down on some lax elements in external tag access, which caused some reverse-engineered drivers to become unstable, and required many other third party HMI drivers to make changes, even if they had engineering cooperation with Rockwell.

If you look at the LTS module downloads at Inductive Automation, you will see some of the Logix 5000 drivers with the parenthetical "v21 support" in the name:

https://inductiveautomation.com/downloads/lts

You might check that the speed/duplex settings match the switch port, I.e. not at AutoConnect or both at 100/Full