L2TP only works from Android

Gloria Gu 3,891 Reputation points
2020-07-15T06:32:11.483+00:00

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

EDIT:

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

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  1. Candy Luo 12,656 Reputation points Microsoft Vendor
    2020-07-15T07:07:36.303+00:00

    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:

    https://github.com/hwdsl2/setup-ipsec-vpn/blob/master/docs/clients.md#windows

    https://superuser.com/questions/1298513/l2tp-ipsec-vpn-fails-to-connect-on-windows-10-works-fine-on-ios

    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,

    Candy

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