I know it's been out for a little while now, but this morning I finally decided to upgrade my Windows 10 laptop with Creators Update version 1703. Everything went smooth, but there was one issue that I noticed immediately after the upgrade! I could no longer connect to any L2TP VPN connections!
The good news is that it was relatively easy to fix. The first thing I tried was I went into Device Manager > Network Adapters and I uninstalled all of the WAN Miniport adapters by right clicking on each one and selecting Uninstall.
I tried connecting to my L2TP VPN after that, but received the following error:
The network connection between your computer and the VPN server could not be established because the remote server is not responding. This could be because one of the network devices (e.g, firewalls, NAT, routers, etc) between your computer and the remote server is not configured to allow VPN connections. Please contact your Administrator or your service provider to determine which device may be causing the problem.
Luckily, this is an error I've seen before and just requires a simple registry entry to allow UDP Encapsulation for L2TP when you are behind a NAT firewall. You can set that registry entry by doing the following:
- Right-click on the Start icon and select Run
- Type regedit and click OK
- Navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\PolicyAgent
- In the right pane, right click and select New > DWORD (32-bit value)
- Name it AssumeUDPEncapsulationContextOnSendRule and set the value to 2