I'm not sure what would cause the MS virtual Ethernet adapter to show an error. What type of error? A yellow bang in the device manager? What's the error say. (I suppose the error will be something generic, but maybe I will get an idea.) I'm definitely not an expert on troubleshooting Hyper-V, but I understand enough theory to possibly give out dangerous advice. So I understand if you don't want to take what I say next seriously.
Here is what I am thinking. Maybe the virtual adapter thinks that the virtual switch configured for the second X520 port is not available for some reason. Was the port configured as a secondary port for iSCSI boot at some point that made Hyper-V look at the port as an iSCSI port and not available?
You might need some help from Microsoft on the virtual port issue, but here is something that I might try. Delete the virtual switch that is using the main communication port on the X520. Make sure that the port is not configured to be used for remote boot. Create a new virtual switch for the port and assign the VM to the switch. Hopefully the error will go away.
I will also check with someone that I know who has more Hyper-V experience than me to see if he has some other ideas?
Mark H
