Home router with battery back up

Hello, I am looking for a modem/router to install and run 24/24h and 365days/year unattended in the home by the sea. I am looking for a device working with the main power line (220V) but also with a battery back up included.

For security needs I wish that in case the main power goes off the router/modem can still work for several hours so it can forward me any automatic alarm messages coming from a security camera and or other home appliances.

I understood that portable modem/router are not the right solution because they are not designed (generally speaking) to run 24/24 and 365/year.

A portable device I have today (not a Netgear) has died after less than 4 years working.

I need to cover 60sq meters of a flat on a single floor and up to 4-6max devices, Apple.

Thank you per your suggestions.