I figured it might be a driver issue so I opened up Device Manager and sure enough, under the network adapters section there were yellow exclamation marks next to every one of the WAN Miniports that show up after you try to connect to a VPN.
I found varying reports of how to fix the problem but here's what worked for me.
- Try to connect to a VPN that will cause things to error out (the WAN Miniports didn't even show up in the network adapter list for me until I did this)
- Open Device Manager
- Expand "Network adapters"
- Right-click every one of the WAN Miniport devices (I even did the ones that didn't have a yellow exclamation point next to them) and do the following:
- Click "Update Driver Software"
- Click "Browse my computer for driver software"
- Click "Let me pick from a list of device drivers on my computer"
- Uncheck the "Show compatible hardware" box
- Under Manufacturer choose Microsoft
- Under Network Adapter choose "Microsoft KM-Test Loopback Adapter" (technically from what I understand you can pick anything that you can uninstall, but this one worked consistently for me)
- Click "Next"
- Ignore the "blah blah might be incompatbile" warning and click OK
- After Device Manager refreshes, right click the Microsoft KM-Test Loopback Adapter and click "Uninstall"
- After you've done that for every one of the WAN Miniports listed, reboot the machine. If you don't do this things won't be fixed.
That cleaned things up for me. We'll see if it works on subsequent reboots.