Windows ICS, PPTP VPN. How will routing and NAT work?

Question

Windows

There is a computer on Windows 7 Pro with two network adapters, acting as a router between the local network and the Internet. For Internet access, a static IP address is provided via IPoE. The Internet Connection Sharing service is being used.

If we connect via PPTP (or L2TP, SSTP) to the VPN server on this router on Windows and use the main gateway of the remote network (all traffic in the VPN tunnel):

1. Which route will the packets from the local network behind the router on Windows take? Will they be directed to the VPN tunnel?
2. Will masquerading be applied to packets from the local network?
3. And if we do not use the "remote network gateway" on the Windows router, and write routes to remote networks manually via route add? Will the principles of operation from questions 1 and 2 change?

Answer 1

ICS is a very sparse mechanism that provides "connection sharing" (through NAT) and nothing else. By activating it for an interface you choose which other interface will be shared. Dull and primitive. He doesn't care about the routing table, nor does he care about other connections.
If you want to make a router out of win7 (there is nothing for you to do) - you DO NOT need the ICS mechanism, you need to enable IP Forwarding, which is responsible for one single registry setting: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\ Services\Tcpip\Parameters\IPEnableRouter
NAT is configured separately via netsh.