The process of activating the L2TP in windows 10 is simple. Just follow the following steps:
L2TP VPN can not connect on Windows 10
You need to right-click on the routing and remote access management console and after that select Properties.
Then you need to select the security tab and check the box that says Allow custom IPsec policy for L2TP/IKEv2 Connections.
Now enter the preshared key and you are good to go.
Read more about L2TP here: