I needed to test some new infrastructure software, so I opened up Hyper-V manager on my Windows 10 desktop and started deploying some VM’s. First I had to setup a simple lab and came to the point where I needed an internet connection in my lab. I remembered that this was a problem under Windows 8.1, but I hoped that Microsoft would have fixed it in Windows 10. Unfortunately they hadn’t, so I had to choose one of the different workarounds.

I chose the workaround with internet connection sharing, as this approach was the quickest way to get some results. I setup a VM with Pfsense and 2 nics, and it all worked perfectly. However the next morning when I wanted to pick up where I left off the day before, I couldn’t get a DHCP address on the WAN interface of my Pfsense VM, and therefore no internet.

I looked at the network configuration of the host adapters in Hyper-V and in Windows 10, also at the settings for ICS, but everything looked okay, so it had to be a problem in the VM or the configuration of Pfsense. I tried multiple things like static addresses, extra gateways and routes, extra firewall rules, etc. It took lots of hours, but all without result. Desperate to find the solution I took a deeper look into Internet Connection Sharing, as this component must be acting as a DHCP-server.

At first sight there was not much to configure and you couldn’t do anything wrong, so I tried a “netsh winsock reset” hoping that would resolve the problem, but still no internet. Then I saw something fishy. When ICS was disabled, I didn’t have a dropdown box and when it was enabled from boot, it showed the shared network, but still no dropdown box.

So I disabled ICS, clicked “OK”, reopened ICS, enabled it and clicked “OK”. After that everything started working again. I got DHCP leases and got internet in my lab.

So even in the latest version of Windows 10 (build: 14393.187) there are still some glitches.