If you have noticed a Wi-Fi signal blind spot in a corner of your home, an old Android phone sitting in your drawer could actually help bridge the gap as a super-easy way to extend connectivity without spending a cent. The approach is straightforward enough that most people can set it up in minutes, and it costs nothing beyond what you already own.
This became possible with Android 9, which added the framework for Station/Access Point (STA/AP) concurrency, allowing a phone to stay connected to Wi-Fi while also running a hotspot. Most Android smartphones released in the last three to four years have the required hardware for repeating a Wi-Fi network via their hotspot. Before that era, your device could only turn into a Wi-Fi hotspot if you first enabled mobile data and used your cellular network's plan, and enabling a hotspot often meant that Wi-Fi would turn off automatically.
Setting up an old Android phone as a repeater differs slightly by manufacturer, but the principle remains the same. The easiest way to turn your smartphone into a Wi-Fi extender is to use the built-in Wi-Fi hotspot feature running on Android OS, though not all smartphones allow you to turn on Wi-Fi and hotspot connectivity at the same time due to hardware limitations, and this capability is more commonly supported in smartphones running stock Android, such as Google Pixel and Motorola handsets, especially newer models. For Google Pixel and Motorola devices, navigate to Settings greater-than Network greater-than Internet, connect to the Wi-Fi you wish to share, then go back to the Network greater-than Internet settings and tap on Hotspot greater-than tethering, and enable the toggle next to the Wi-Fi hotspot. Samsung phones may require a different path; head to Settings greater-than Connections greater-than Wi-Fi and connect to the Wi-Fi network you wish to extend.
For phones that don't support the feature out of the box, if your smartphone does not support simultaneous Wi-Fi and hotspot connections, activating developer options offers another option; for Galaxy devices, go to Android phone greater-than Software information greater-than tap seven times on Build number, go back to the main Settings screen, select System, tap on Developer options, and search for Enable Wi-Fi Coverage Extend Feature and enable it.
Understanding the limitations matters before you rely on this solution. The signal won't be anywhere near as strong as what you can get with a real Wi-Fi repeater, as phones simply aren't designed to act as Wi-Fi repeaters. There is a limit to the reach of the Wi-Fi signal extended by an Android smartphone; it can work flawlessly for up to 15 metres or so, but not more. Since you are routing a Wi-Fi connection through a phone, it can hamper the speeds on the second phone or computer, so don't expect to run heavy downloads or do video streaming, but it will be good enough for casual work and web browsing.
Practical considerations will determine whether this approach fits your situation. If you plan to use the old phone as a repeater for an extended period, make sure to plug it into a nearby outlet, as running a hotspot can drain the battery quickly, and place the phone in a cool, ventilated area to prevent overheating, as many phones will automatically shut down the hotspot if they get too hot. Placement of your extender phone is important; keep it at the place where the signal is weakest to augment it, extending the network's reach effectively.
For those with older devices or problematic hardware, most Android phones have a built-in setting to use it as a Wi-Fi extender, but if your phone doesn't have it, use the NetShare app from the Play Store. However, if your device is missing a Wi-Fi extender feature, downloading a third-party app from the Google Play Store is an option, though since last updating, none of the apps found on the Play Store managed to do what they promised at least not without root access to the device's hardware, and you should warn against installing third-party apps that promise to transform your phone into a Wi-Fi repeater, extender, etc.
The practical reality is that this method works best as a temporary solution for specific problem areas. Using the feature as a temporary solution to poor reception is recommended only if your smartphone supports it; for example, if you don't receive proper Wi-Fi coverage in a part of your house, you can turn your phone into a network repeater and place it between the area and your router. It offers genuine value for households with single dead zones, outdoor areas that fall outside router range, or situations where upgrading to mesh systems or dedicated repeaters isn't practical right now.