Troubleshooting L2TP ISP Connectivity Issues

L2TP connection setup is tracked in the log. Check the log (Log > View page of the SonicWall's user interface) for messages to assist in determining the problem with L2TP initialization. There are log messages regarding:

• L2TP Connection Initiated
• L2TP Session or Tunnel Negotiation Started
• L2TP PPP Authentication Failed

Attempt the following troubleshooting steps if you cannot establish an initial connection to your ISP:

• Ensure proper power connections. Ensure the correct SonicWall power supply is being used if external (5V, 2.4A rating: except the TZ150 which is 12V, 1.66A).
• Check the WAN link light. If there is no link, check the cables to the DSL/Cable modem and verify the ports are OK.
• Try rebooting the DSL/Cable modem and the SonicWall. (Some modems require reboot whenever SonicWall reboots.
• Ensure there is no DSL/Cable modem or line problem. (no L2TP negotiations)
• Ensure the username and password are correct (authentication success or failure).
• Verify you get a proper IP lease and can ping the ISP gateway from the SonicWall. If not, contact your ISP.
• Try connecting directly with another host or PC. If this does not work, contact your ISP.
• Ask your ISP if they have measures that prevent you from switching equipment. The ISP may lock IP assignments to MAC addresses.