Upgrading Windows 10 Disconnect your VMs?

So how many of you upgraded your machines to Windows 10 Technical Preview? Go ahead ... raise your hands. I will! My work desktop is a lovely Dell Precision T7610 with Core i7 processor, 32 GB of RAM, 2 TB of storage and nice dual monitors form me to spread my work out onto. The Windows 10 Technical Preview program has been great on this rig and I can't wait to see what the team will do next.

However, I came in this Monday and started to do some work on my Hyper-V Virtual Machines that I host on this system. With 32 GB of RAM and dual NICs, I setup one for all of my VMs to connect while the other NIC is for my main OS. However, none of my VMs could get out of the main box. I checked and the cables were all plugged in. The system looked happy. What was I to do?

First, I noticed that the virtual NIC on the VMs showed that the cable was "disconnected". Now, I am a bit slow on the uptake sometime but how can a virtual NIC connected to a virtual switch be disconnected. Looking through my system, I couldn't find a virtual cable that I had to plug in. Maybe that will be something for HoloLens but I couldn't tell you because I haven't gotten my rig yet. So, that indicator gave me a suspicion around the connectivity.

Second, I went into the NIC settings on the computer/VM host to validate that the NIC was indeed connected to the network and it was happy there. Of course, it was happy and said that all should be well. This led me to think that the virtual switch was not working right.

Third, I went into the VM settings for the NICs and "removed" the cable setting the virtual switch to "Not Connected" applying that setting. After doing that, I put the setting back to my virtual switch that I use for my network connectivity ... still no go. Something tells me this is the switch.

Taking in my work so far, I set all VMs using this virtual switch to "Not Connected", thus unplugging them from the virtual switch. I removed the virtual switch and saved the settings. Then, I created a new virtual switch connected to that NIC validating that all settings worked. Once the virtual switch was recreated, I "plugged" the virtual machines in. Logging in to each machine, I verified that indeed all connectivity was returned and they were all happy. Good thing too as I needed to test some RegEx expressions for IIS URL Rewrite Tool.

I hope this helps you in your troubleshooting and maybe gives you a quick resolution to check prior to more troubleshooting.