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VPN L2TP issue with Windows 10

thomas chevalier

I would like to get some help.

I am trying to create a L2TP VPN for a remote user.      

So far, i have done the VPN configuration, and Firewall rules (to be able to acces to my internal network)

 

Until now, i am only able to connect to the VPN with my IPhone. (and i can access to my network without trouble)

But when i try to connect to the VPN with my laptop, i always have an error message : the L2TP connection attempt failed because the security layer encountered a processing error during the initial negotiations with the remote computer.

 

For the VPN configuration, I am using the “DefaultL2TP” Policy

I do the authentification with a preshared Key

For the test, I have disable the firewall of my laptop.

 

Have you an idea about how can I make it works with my laptop?

I am trying too to connect the VPN on my laptop as using my IPhone as router, but i have the same error message.

 

Thanks for your answer ,

 

Best regards,



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  • 0

    Hi Thomas,

    The error message: "The L2TP connection attempt failed because the security layer encountered a processing error during initial negotiations with the remote computer" is a generic error to identify when the IPSec negotiation fails for L2TP/IPSec connections.

    Which authentication method is selected on your Windows VPN Settings (PAP, CHAP, MS-CHAPv2)?

    Try playing around with the authentication methods to see if one works over another for your laptop and please update me with your findings. 

    Thanks,
    Karlos

  • 0 in reply to Karlos

    Hi Karlos,

     

    Thanks for your answer.

     

    So far, i was trying to connect with the MS-CHAPV2.

    This morning i was trying the CHAP and then the PAP authetification method.

    But i still have the same result.

    I even don't have any log on my router.

     

    Yesterday evening, i have also tried with a personal laptop that is in Windows 7. (it couldn't connect either) (i was home with a personal WIFI, Firewall OFF )

     

    I am still able to connect with my Iphone (with the DATA or WIFI)

    This is the log from my IPhone on the Router :

     

    Thanks for your help,

     

    Best regards,

  • 0 in reply to thomas chevalier

    Hi Markos,

     

    I have figure out why it doesn't work.

    It was something i have never expected, on all my windows 10 laptop, the services "IKE key generation module and AuthIP" and "IPSEC policy agent" were disable .

    I could connect by VPN my laptop.

     

    I am going to do more test tomorrow .

     

    Thanks,

     

    Best regards,

  • 0

    This might help

     

    Deleted my last update as it was inaccurate.  I narrowed it down to a NAT issue (as when DMZ mode is enabled, it's as if the server has a public IP and will work.  Once it is behind the firewall, then it will allow only one client and the rest seem to not be able to communicate due to the NAT issue.  Any ideas why this would be? Is there something I'm overlooking?

    Edit: Solved.  It wouldn't allow simultaneous connections because I had it set up for my server to listen to port 4500 for only connections coming from port 4500.  So because I already had one connection in, the port was closed.  To fix, just had to change the source port to "any" and forward to 4500.  Now on to error 789 =)