L2TP only works from Android

Gloria Gu 3,811 Reputation points

Hi All,

maybe someone knows how to approach this.

VPN server configured on windows server 2016

Clients can use pptp no problem.

I try to switch to L2TP but I can only connect from android phone (4g and wifi)

When I connect from windows 10 PRO ver 1909 "connecting" spins for minute or two and nothing happens. or I get error.

"How to troubleshoot a Microsoft L2TP/IPSec virtual private network client connection" at https://support.microsoft.com/en-us/help/325034/how-to-troubleshoot-a-microsoft-l2tp-ipsec-virtual-private-network-cli was not very useful.

Also I followed "L2TP/IPsec VPN On Windows Server 2016 Complete Lab (V2.0" https://gallery.technet.microsoft.com/L2TPIPsec-VPN-On-Windows-5cc2c3ae?redir=0

First I though this is server side error but if android phone can connect then how come windows pcs and iphone fail?

event viewer:

server: nothing l2tp related

client: same


I Am able to connect to vpn server from Windows 10 PC via LAN but still can't connect from internet see screenshot:

I would love to blame router but how come then I am able to connect from android via 4g?

Thread source link: https://social.technet.microsoft.com/Forums/zh-CN/4c456869-193f-456e-8e89-46dfa98002f1/l2tp-only-works-from-android?forum=winserverPN

Windows Network
Windows Network
Windows: A family of Microsoft operating systems that run across personal computers, tablets, laptops, phones, internet of things devices, self-contained mixed reality headsets, large collaboration screens, and other devices.Network: A group of devices that communicate either wirelessly or via a physical connection.
237 questions
No comments
{count} votes

Accepted answer
  1. Candy Luo 12,451 Reputation points

    Hi ,

    Welcome to our new Microsoft Q&A Platform.

    >>When I connect from windows 10 PRO ver 1909 "connecting" spins for minute or two and nothing happens. or I get error.

    Please make registry fix and then reboot computer.

    You can run the following command:

    REG ADD HKLM\SYSTEM\CurrentControlSet\Services\PolicyAgent /v AssumeUDPEncapsulationContextOnSendRule /t REG_DWORD /d 0x2 /f

    Please remember to allow CHAP&MS-CHAP v2 protocols.

    You can refer the following link:



    Please Note: Since the website is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.

    Best Regards,


    No comments

0 additional answers

Sort by: Most helpful