Users trying to connect via L2TP from a Chromebook fail to connect and get a "Connect Failed" error. This happens because pursuant to Google's documentation Chromebooks do not support XAUTH Authentication in any capacity. XAUTH is the default Authentication method for VPN Users on the SonicWall and this will lead to compatibility issues. Below is an exerpt from the Glboal VPN Client Logs that you're likely to see when connecting to the SonicWall VPN via Chromebook and attempting to use XAUTH:
NOTE: These Logs are captured when trying to connect and observing the subsequent failure.
4500 VPN Pol... Received IKE SA delete request
4500 VPN Pol... Received IPsec SA delete request
4500 RECEIVED<<< ISAKMP OAK INFO (InitCookie:0x7cxxxxxxxxxx RespCookie:0x6addfxxxxxxxxx...
4500 VPN Pol... IKE negotiation complete. Adding IPsec SA. (Phase 2)
4500 VPN Pol... IKE Responder: Accepting IPsec proposal (Phase 2)
4500 VPN Pol... IKE Responder: Received Quick Mode Request (Phase 2)
4500 VPN Pol... IKE Responder: Main Mode complete (Phase 1)