Both VPN sites are in the same IP range

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Q: Both sites are in the same IP range

I have a LAN in a site that connects to Internet by mean of an ISP. The server in that LAN shares Internet access to all LAN computers using ICS/ICF. Since I have ICS, the server was assigned the IP 192.168.0.1. Let's name this site as S1.

I have other site that connects to Internet using other ISP. The server shares Internet using RRAS/NAT configured as a VPN. This server is also assigned IP 192.168.0.1. Let's name this site as S2.

When I establish the VPN connection from S1 (the client) to S2, all S1 LAN computers lost connectivity to Internet (but not among them). I think it is because of IP conflict among servers of S1 and S2.. What is the best way to manage this to work?

A: You will not be able to do this with a VPN connection if both subnets are using the same IP subnet.

What you are setting up is a LAN to LAN (also called router to router) VPN. The VPN connection links the sites, and the RRAS routers forward traffic between the two subnets across the link. Because it is a routed connection, the two sites must be in different subnets. It will not work as
a bridge. (A bridge is a connection between segments which are in the same IP subnet).