I have set up and connected to a PPTP VPN on our Archer A7 router.  By some miracle, I can make the connection using Windows built-in client, then type the IP address of the computer I usually need to access in the address bar in Windows Explorer, and I can then browse that machine as if I were on the network.  The problem is that this approach seems to only work for that one IP address.  This is probably something very easy, but I have a very limited knowledge of networking and even less of VPNs.  

How can I troubleshoot this so that I can connect to other machines as well?

Possible issues:  

• My home network and the target network are both on 192.168.1.*.  Most IPs are between 100 and 200 on both, but the machine I can connect to is on 80.

• We are running a peer-to-peer network on Windows 10 on the target network, and browsing machines on that has never worked great in the first place.

Thanks for any suggestions you could provide!