it sounds like your VPN is only allowing you to access devices that are on your own network.
There are a few ways around this:
- Set your computer to use a Proxy server on the network your VPN connects to (if there is one available)
- Get your VPN changed to support hairpinning
- Get your VPN changed to support Split Tunnelling
Wayne
Please remember to mark helpful responses and to set your question as answered if appropriate.