How to connect one ip in a remote network to VPN via mikrotik?

Question

VPN

There are two networks, let's call them "main" and "second"
On the main network, the l2tp building was raised. The second network has a video surveillance recorder.
The task is to hook up this particular registrar to vpn in order to be able to watch cameras from the main network.
Ideally, the registrar should use the local Internet, but at the same time have its own ip in the main network

Answer 1

"had his own ip in the main network" - I don't understand why?
Access to the registrar can be obtained in two ways
1. If the "second network" has an external IP - an elementary NAT rule. In order not to release the registrar to the entire Internet, specify the Src Address of the "main network"
2. On the router of the "second network", raise the l2tp client, register routes in IP Routes. If you don't want to see the entire "second network", write down only the IP address of the registrar instead of 0/24

Answer 2

TheBigBear Yes, the second network has a white ip, please tell me what the rule is.
And as I understand it, it will be necessary to forward the port?