I have a Vigor 2800VG running firmware 2.8.2 E.38.2.23 Annex A Build Date/Time : Tue Jun 3 15:26:55.35 2008.

I am using a 3 UK USB mobile dongle for failover backup.

I was sure I had Dial Backup Mode: None as shown on the 3G Data Setup FAQ page, and below that was a link: Go to 3G USB Modem Backup Setup. I used that link, configured the 3G connection and it worked whenever there was an ADSL outage.

At some point, presumably during/after I reconfigured the router to use ADSL2+ on a new ISP TalkTalk during which I installed the current firmware, the "Go to 3G USB Modem Backup Setup" option disappeared from the PPPoA/PPPoE setip page. However I can get it to appear if I select Dial Backup Mode: Packet Trigger.

My question is: which is the correct Dial Backup Mode option to have the 3G backup activate only when the main ADSL is down, and why does the link to the 3G modem setup disappear when None is selected? It makes sort of sense - if set to None you aren't using it - but the FAQ screenshot shows it set to None and I'm sure I've never used any other setting.