L2TP VPN can not connect on Windows 10

I am new vpn user and I have configured an L2TP server with a shared key on my laptop. I have tried numerous ways like disabling of firewall but it can’t connect. Anyone can help me.

PPTP or IPSec? The former is hopefully not supported at all, as it has been revealed to have severe security faults.

IPSec. I think that is why I am facing the issue. But I read many guide regarding l2tp like
https://www.vpngate.net/en/howto_l2tp.aspx



In every guide they just mention the setup not provide any proper solution.

Confirm that you aren’t blocking and are forwarding the protocols involved. As I recall, they are 50 and 51 for ESP and AH, respectively. Since you’re going through NAT, you may need to forward the ISAKMP UDP on port 500 as well (though many devices, especially those intended for non-technical users, such as micro-cells and VOIP boxes, have ways of opening the UDP port when needed to the specific server and port associated with the IPSEC connection).

How could I confirm? I don’t have enough knowledge. Please assist me step by step.