Virtual networking is very interesting. I ran into the issue with applying an external virtual switch to an interface within Hyper-V Server 2008 R2 when still using that interface to access the server. This seems obvious, but since the cards can sometimes grab DHCP, you may find yourself in this predicament. The error I received was:
"error applying new virtual network changes", with "binding to external Ethernet... failed". "Cannot bind to ... because it is already bound to another virtual network".
To fix it I opened the command prompt on Hyper-V Server 2008 R2 and ran:
- netcfg -u vms_pp
- netcfg -l c:windowswinsxsamd64_wvms_pp.inf_31bf3856ad364e35_6.1.7600.16385_
none_beda85050b13680cwvms_pp.inf -c p -i vms_pp
Have a good day.