Can a wifi router be used as an extender?

Yes, most wifi routers can be used as extenders, though the setup depends on the model. Many TP-Link, Netgear, and Asus routers have a "repeater" or "access point" mode buried in the settings. You log into the admin panel, switch the operating mode, and connect it to your primary router's wifi network. It then rebroadcasts the signal to cover dead zones.

That said, using any router as an extender isn't ideal. In repeater mode, the router uses the same radio to receive and retransmit the signal, which halves your bandwidth. That's true whether it's a five-year-old router or one you bought yesterday. A dedicated mesh system or a proper access point connected via Ethernet cable will always outperform a router running in repeater mode. If you've got a spare router lying around, it's a free fix worth trying before spending money. But if you're buying a new device specifically to extend coverage, get a mesh unit or access point instead.