How to use an old Android phone as a backup for your home router

Hot weather and stretched infrastructure can knock out power and phone lines, so having a router-level fallback keeps every device on the network connected without changing Wi‑Fi credentials on each one. Using a smartphone as the router's upstream link avoids the hassle of switching every gadget to a phone hotspot.

There are three practical approaches. USB tethering uses a USB‑A to USB‑C cable from the phone to a router USB port and enabling USB tethering in Settings > Network & internet > Hotspot & tethering; many routers detect this as a WAN Ethernet connection, though basic ISP-supplied models may not.

Installing OpenWrt or DD‑WRT can add compatibility and extra features. Some routers support WWAN (Wi‑Fi as WAN), letting them join a phone hotspot while remaining the main router. This feature is uncommon but built into many travel routers from GL.iNet and present on some Draytek and Ubiquiti UniFi models; OpenWrt or DD‑WRT can also help enable it.

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