My Main Router: Asus 68U Router (was now dead)
Backup 1: NetGear XR500 (IPV6 issues and i never liked the DumaOS interface (not suitable for backup)
Backup 2: Telstra gateway 1 (TG799vac) - 11 years old and still works fantastic (only 1 now using currently)
More so with covid spreading around you can't just go to the store and buy 1 asap,
Shopping online is way safer just make sure you disinfect the package when you get it

So what are your backup modem/routers for NBN tech ?
edit: added changes due to modem dying and other being crap