Hello,
We've recently had a problem appear across our Hyper-V 2008 R2 and 2012 clusters. When a virtual machine is rebooted, some of its virtual network cards will have no network connection. The VMs run 2008 R2 and 2012, both of which are affected.
Some VMs have 4 virtual NICs and different ones will lose connection randomly, it can take 4 reboots before all of them are working. The problem happens as soon as the VM comes up after a reboot, the network shows as connected in Windows, yet no traffic will pass through it. Running an ipconfig on the affected VM will show 2 IP addresses for each NIC with no connection - the normal static address and an autoconfiguration 169 address.
The hosts and VMs are all up-to-date with the latest patches, integration services have been updated on all the VMs and there are no errors showing in the event logs. I've tried reinstalling the virtual NICs, created a new virtual switch, disabling offloading and disabling VMQ but nothing has helped. Once all the virtual NICs are connected, they don't have any more problems until the next reboot.
I'm really stuck with this one now. Any advice would be appreciated.