A common problem with Remote Access VPN connections is how to force DNS name resolution across the VPN tunnel. With Windows you will likely need to modify the Windows DNS Client behavior by changing the Network Interface Binding Order (older versions of Windows), or Network Interface Metric (Windows 10).
According to the Microsoft Networking Support Team, “The only known component that used the binding order was DNS ordering. By default, Windows uses the Route Metric + Interface Metric to determine which route has the highest priority by choosing the route with the lowest value.” Because of this, you may need to adjust the interface metric(s) using GUI, PowerShell (Set-NetIPInterface -InterfaceMetric), or netsh (int ip set inerface=”…” metric=…) to ensure that the VPN connection(s) automatically assigned metric will be lower (preferred) over any wired or wireless connection you may be using to access the Internet on your computer.
For reference, here are two StackExchange Q&A discussions of the problem and solution options.
- How does Windows decides which DNS Server to use when resolving names? (serverfault.com)
- Windows 10 DNS resolution via VPN connection not working (superuser.com)
An important note is that when adjusting the interface metric(s) on Windows 10, you should only adjust the metric on NON-VPN interfaces since the VPN interface metric will be reset automatically every time you connect. Base the setting of your other interface metric on the automatic value you see assigned to your VPN connection so that the VPN will always be preferred (lower metric).
Good luck with your Windows VPN DNS troubleshooting and repair tasking! 🙂