NBN router 4G backup/failover

For our business we have a telstra netgear V7610 router. It came with a 4G USB modem/dongle for use as a backup. This is meant to automatically swictch over if the ADSL/VDSL/NBN connection goes down. It has a section in the manual of how to set it up:

Telstra V7610 Manual

Has anyone had any success in getting this to work? I've set it up with the following settings:

It seems to read the modems 4G reception:

It seems it  isn't able to connect though:

I would be very much appreciative if anyone could shed some light on the issue. 

The modem works fine plugged into a PC.

All the telstra people haven't been that helpful in fixing this.

Cheers,

Richard