There are two types of VPN - Tunnel-only, where all traffic is directed through the tunnel, and Tunnel/open, where certain communications are managed through the VPN tunnel, but the device is open to access other resources on the LAN/Internet.
Our work VPN became Tunnel-Only not long back, so in my home office, my work laptop cannot be accessed, nor can it access any local resources (printers, local machine sharing, etc) or internet resource outside of the tunnel connection while connected to the VPN.
Previously, it was in the Tunnel/open, where the VPN connection provided access to my work's intranet, but I could also connect to other computers & printers on my LAN as well as access the 'net via my ISP.
If you are looking for a secure VPN, all communications must be routed through the VPN tunnel-only. Else, you probably have no idea what is connecting to what...