Hello, this is Martín, Tech Support Engineer for Teltonika Networks.
As I understand, your base station is comprised by a TRB245, the camera and the computer connected trough RS232; and your remote station has a TRB245 and a computer attached to it.
If so, a solution that would allow connectivity between your base and remote stations would be to create a VPN Hub trough RMS, connect both the base station and the remote station to it, and after you have verified the connectivity between devices you could enable the Serial-Over-IP mode in the settings of the remote station using the corresponding IP addresses set up on the VPN Hub.
This would allow you to connect from the remote station to the base station trough the VPN, and to get serial connectivity on the PC on the base station, when you connect as a client trough a software like Putty. This solution also expands the connectivity of your device to any client which connects to the VPN by using an OpenVPN client.
I'm attaching the corresponding links below:
VPN Hubs: Wiki Article, Instructional Video
RS232 Over IP: Wiki Article