I am preparing our Hyper-V SQL server for migration to a new Hyper-V CSV cluster. It has 2 VNICS one to our LAN, one to a SAN LUN. I have since virtualised the SAN LUN and placed it locally on the Hyper-V server in preparation for the move. However when I disable the internal SAN NIC none of our SQL clients (IIS7 etc.) can connect to the server. They connect using \\servername\instancename. I have to get rid of the NIC, it's not needed in the Cluster environment. The SAN has no routes, only the LAN does. All the other servers can ping each other whether the SAN NIC is disabled or not. I've tried various combinations of enabling IP protocols in SQL server config, no luck. The only thing that matters is that SAN NIC.