If a VDI is having trouble reaching expected endpoints then these are the two simplest ways of diagnosing the problem.
Check the VDI's static IP
The 10.8.0.X address should match the assigned IP for the user that reserved the VDI (found via the image below)
This private IP is how ACLs are applied, so if it is wrong then the ACLs for the VDI will be wrong.
Ping to confirm VPN access:
ping 10.8.0.1
If this ping fails then it means the VDI is not connected to the region.
In both cases reserving a new VDI should resolve your issue. If both tests pass, or consistently fail, and you still have issues please reach out to dispel to diagnose a deeper problem via the chat bubble in the bottom right or by sending an email to support@dispel.io.