ABControlLogixTransport Unsuccessful Forward Open

I am recieving this message for a device that appears to be in good health. The Scan class is also struggling, taking up to 30 seconds to complete 25K tags. v7.6.2
Any suggestions on finding the root cause here?

What rate is the scan class at? Can you follow the diagnostics link next to the device in the gateway and attach a screenshot of that page? How many concurrent requests is the device configured for?