I need to know the best mordern method of Linking PCs cross-office.

I have a main server in my office which controlls all the other PCs. I also have a link that helps me work from home through a VPN connection and this requires the Server to be left on.

I also want to open another office that will also be accessing this same data from the existing server. As it is VPN server is not the best option for accomplishing this work full time.

I need your suggestions on the way forward, I prefer to use the latest in technology.