I have the same problem and am told that it is because the WINS service on our work laptops are connecting to my employers version when connected to their WAN/LAN and the devices are completely unknown on that network.

For printers, the only way I have found of getting access to any of the devices is by IP address in the same way that our networked printers work. I had a small print server which had a 'name' rather than just an IP and we could only use that printer when the VPN service was dropped. As soon as VPN was reconnected the laptops tried to find the device on the employers service and of course it wasn't there. We now have a new router with a print server built in which has no name, only an IP and it works fine.

Have you tried creating new printer ports with your home network IPs associated with the printers to see if that will work? It may also be that there is a setting in the VPN software (we use a Cisco version) that has the local LAN access disabled? Every so often a service patch is issued by our employers with local access disabled which causes us to lose our printing until the function is enabled again.

I cannot connect to either the MediaSmart 475 or MediaVault MV2020, but I can 'ping' both IPs with no trouble once the VPN is off. It may be a case of adding the devices to a trusted network on the laptop firewall, but that breaches the security rules!!