Thanks for the reply. Unfortunately, I can't install anything on the 3 pieces of equipment (or otherwise modify them), which makes it harder. They run an old version of windows embedded (not a full implementation of windows).
So, the new piece of networking gear I introduce (a VPN router or whatever) needs to take care of the details somehow...
I don't need to get onto those pieces of equipment (so a remote login or remote desktop kind of approach is not what I'm looking for) - I just need to be on their network. They are monitored through proprietary software over TCP/IP so I just have to be able to see them on the network. I will run the software on my PC and it will talk to these devices and do whatever it is that it needs to do.