After upgrading to Vsphere 5.1 1 of my ESXi Hosts cannot be added to the vDS. It can be added to the vSS with no problem. Also once you remove it from the vDS you can't add it back. I have tried removing ot totally from Vcenter and then using vDS to add it back.
To no avail...still can't connect to vDS.
Any suggestions out there???????