So - I don't actually have a problem, but I'm really curious, because apparently VPN's don't work the way I thought they did.
It was my impression that when I VPN into my office, my computer is essentially isolated so that I can no longer connect to computers on my local physical network, and that instead, everything is tunneled to where I work, so that it's very similar to me just physically bringing my home computer to work and plugging it into the network there.
At home, I recently set up Input Director so when I bring my work laptop home, I can just place it next to my home PC, and I can use the same keyboard and mouse for both machines seamlessly. I thought that when I enabled VPN on one of the two machines, ID would fail and would be unable to stay connected while the VPN session was active, but it works fine. I even tried each computer separately, the slave and the master, and it still worked.
When I have my home desktop VPN'd in, I noticed I can still ping my laptop, but the laptop can no longer ping the home desktop once the VPN is turned on (using 192.168 addresses from ipconfig). The laptop is normally on the work domain, the home desktop is not.
What is happening here? Is this a configurable aspect of VPNs that varies from set up to set up? Is this behavior a security problem? What is it about VPNs that I don't understand that is making me confused?