I have a network using a FIOs router...I have a linksys router shooting the signal across a lake to another receiving router and off that I take the signal to use in that building on another router. That router uses 192.1681.x
The main building uses 192.168.2.x. I want to have a connection to a pc on the 192.168.1.1 from the main bldg so I can use an external drive there for an off-premise back-up. Do I have to use a VPN to do that?