said by j1349705:Do you have any software firewalls other than the native one that comes with Windows? If so, try removing them. I have seen this exact behavior in multiple occasions. The same thing applies to anything else that installs as a NDIS filter. I know you said nothing has been installed recently, but I have seen this kind of issue occur suddenly for no apparent reason.
If it is not an onboard NIC, do you have a spare you could try? Hardware issues are always a possibility.
Yeah, both on-board. ESET threw an error in the event logs and I removed the AV but it didn't fix anything. I'll try the spare mobo but I have neither the time nor the patience to really troubleshoot it. I'm seriously contemplating making one of the connections active and removing the DC role the blowing it away and start with a fresh install.