Modem Connection fails when using FortiExtender and AT&T Netgear 340U modem

Description

Problem: Modem Connection fails when using FortiExtender and AT&T Netgear 340U modem

Symptom: “get extender modem-status” returns an empty list

Note:  Even upgrading to the newest FortiExtender firmware does not allow the AT&T Netgear 340U to connect.

Root Cause: By default, the 340U modem operates in MBIM (Mobile Broadband Interface Mode). This mode is not natively supported on Linux platforms, including the FortiExtender kernel. It must be disabled by applying a patch to the modem.

Solution
FortiExtender Release Notes mention this special case scenario and point to a modem patch.  Unfortunately, the official website for Netgear 340U no longer has the patch.

The following external forum topic discusses this issue:

http://forums.cnet.com/7723-7585_102-612341/meraki-router-at-t-aircard-question/

Please contact Netgear to request the official patch. Alternatively, contact Fortinet Tech Support and reference this article ID for support.