We have a problem where some users will complain of slow application response time (on the LAN) from our ERP server, but others will be fine. After many hours of troublshooting I've discovered the following:
- Packet Sniff's of affected users shows TCP Retransmissions because the Checksum is Incorrect from the server.
- Replacing the NIC card on the workstation temporarily fixes the errors. Then the problem may start happening on new NIC, so I swap back to old NIC and problem goes away for a while.
- Sometimes the problem clears itself up for certain people after a couple months.
- There is no similarity between NIC cards, drivers, versions, laptops, desktops, wireless.
- Affected users have been tested on different segments of the LAN with no success.