The issue is that when connected to VPN, only a small subset of folders appear in a network drive. For example maybe a network shared drive has 20 folders but when connected to VPN only 3 of those 20 folders appear. This could be due to an Offline Files issue where certain folders are synced between the computer and the server for some reason but the other folders are not. Only the synced folders appear when connected to VPN. You could disable Offline Folders which should stop the sync and force the computer to show all folders or try the following to disable Slow Link Detection and thus prevent Windows from displaying only synced folders.
Disable the Configure Slow-Link Mode Group Policy
Computer Configuration – Administrative Templates – Network – Offline Files – Configure Slow-Link Mode (disable turns it off)
Set Configure Group Policy Slow Link Detection to 0 (All connections are Fast)
Computer Configuration – Administrative Templates – System – Group Policy – Configure Group Policy Slow Link Detection
Setting it to 0 (zero) causes all links to be considered fast
Set Do Not Detect Slow Network Connections
Computer Configuratino – Administrative Templates – System – User Profiles
Disable IPv6 **
Open the VPN Adapter properties and disable IPv6 (uncheck the IPv6 box)
Enabling IPv6 can slow down the VPN connection time and possibly mess with the Slow Link detection
Disable NetBIOS on VPN Adapter **
Disable NetBIOS over TCP/IP by opening the VPN Adapter properties and going to Advanced and WINS tab.
Also disable LMHOSTS lookup
Make sure appropriate DNS Suffix is entered and Register connection in DNS
** These two seem to work after disabling slow link detection. Disabling slow link detection only does not seem to work.