Vodafone mobile backup failed - how to troubleshoot?

[Quartz]

I have Vodafone fibre with a Huawei mobile dongle backup attached to the router (supplied by Vodafone). Last night Vodafone's fibre network failed so I expected the mobile dongle to take over. It didn't. I had no internet connection through it. When I check the Mobile Status page on my router I see that it has no connection - which would explain the no connection - but also the Manufacturer, Model, IMEI, etc fields are blank. So I'm wondering if the problem is more serious and the dongle is broken. How do I test this?

 

[Quartz]

If Vodafone supply the backup then let their support figure it out. Are you sure you're on a package that provides a backup and didn't re-contract to something without one, which would then have led to them cancelling the SIM?

My contract hasn't changed, other than going off the half-price introduction.

 

[Quartz]

Done the obvious thing
And restarted the router?

Yes.