How to merge two networks using l2tp?

Question

VPN

There are two networks as shown in the figure LAN 1 and LAN 2. In LAN 1, the gateway is a cisco router, this cisca has access to the Internet through a firewall, there is access to both pieces of iron. The remote office LAN 2 has a router that only supports GRE, L2TP, IPSec. Internet access in LAN 2 is provided through a gray ip address as shown in the figure.
The question is whether it is possible to combine these two networks through L2TP or other protocols mentioned above. that is, make the cisco in LAN 1 L2TP north from the firewall, forward all the necessary ports to it for l2tp operation and connect to it from the router from the LAN 2 network and then register routes through the tunnel in two directions for two local networks.
If this cannot be done, please suggest ways in which this can be done differently.

Answer 1

Can. You just need to sit down and set up according to the instructions. And there are plenty of ways.

Answer 2

If I understand correctly, then https://nimbus.everhelper.me/client/notes/share/36... will help you set up.