SonicWall’s VPN client won’t connect without adjustment to the default Group VPN policy. A quick check of the client software’s log will display "Failed to find MAC address 00:60:73:xx:xx:xx in the system interfaces table".
What’s happening is VPN client is connecting to the SonicWall but not receiving an IP address from the destination network. While there are numerous other workarounds on SonicWall’s website, we found none of these worked for us. We found the answer in the Group VPN policy settings. The Virtual Adapter setting (found on the Client tab) was set to None preventing connectivity. Setting this to DHCP Lease or DHCP Lease or Manual Configuration corrected the problem.
Oddly enough, we found "none" to be a default setting in the units we manage.