Maybe you can try upgrading DAQmx to the latest version that is still compatible with your OS and LabVIEW. It may fix this issue as the device drivers may have been fixing issues with BIOS and chipset specific things.
Next step after that would be to replace the Ethernet cable. These cables may seem like there is nothing that could go wrong with them, but I have had several cases where things seemed to go randomly bad in networking and replacing the cable with a new high quality one remedied the issue once and for all. Especially if you have cables laying around on the floor and people being able to walk over them, or worse your office chair rolling over them, then you should replace them anyhow and route them in a way where they won't get stressed anymore.
If that still doesn't help you may have to start trying different network interfaces.