Setting up zuxel and tmg connection network-to-network?

Question

VPN

Good day, help with the solution of the issue
1 - There are 3 offices, let's call them office (main) and 2 branches (remote)
TMG + VPN (pptp) is installed and configured in the office (main)
2 network interfaces
1 - wan ip 210.5.xx)
2 - lan (local network ip - 192.168.1.x.)
Branch 1 also deployed TMG + VPN (pptp)
2 network interfaces
1 - wan (Internet is provided via ip 210.18.xx)
2 - lan ( local network ip - 192.168.2.x.)
between branch 1 and the main office everything works fine
, you need to connect branch 2 (network 192.168.3.x) to the main office (via vpn)
in Branch 2 is Keenetic Extra Internet connection is via ppoe (ip static 89.xxx)
Method 1
On Keenetic Extra, a pptp connection over ppoe rises and a connection to the office occurs (like a client-server) but! pings from the local network of the branch reach the network of the main office, but pings from the network of the main office do not reach the network of the branch.
Most likely, in this case, the problem is in the routes, but where and how to register them?
Method 2
A VPN server is installed on Keenetic Extra. A network-to-network connection is configured on the TMG. An encryption error occurs when trying to start this connection! Without encryption, the TMG connection occurs, but: from the network of the main office, the branch network is accessible (pinged) from the branch network, the office network is not pinged)
Method 3
On Keenetic Extra, port forwarding (pptp) has been raised to the server (windows server 2002r2) on which the remote network access service has been raised.
There is only 1 network interface on this machine (ip 192.168.3.200). When raising vpn between the branch (server 2002r2) and the main office (TMG), the ping also goes in one direction from the branch to the main office. from the network of the main office, only the network card is pinged (server 2002r2 ip 192.168.3.200)
As far as I understand, the problem is that routing does not work with one network card?
Interested in method 1 or 3, tell me in which direction to dig ???

Answer 1

see routes on tmg.
1. you need to add internal networks
2. routes to these networks
, all this is done in the "network" section