Wi-Fi connects, works for a while, then drops, and the cycle repeats. A connection that keeps dropping is usually a signal, interference, or power problem rather than a password problem, so the fixes focus on the radio link and the adapter.
The fix, in order
Move closer to the router and remove obstacles. Thick walls, metal, mirrors, and distance all weaken the signal. Test in the same room as the router to see if the drops stop.
Restart the router and the device. A router that has run for weeks can develop a fault that drops clients, and a restart clears it.
Turn off adapter power saving. In Device Manager, right-click the wireless adapter, choose Properties, go to the Power Management tab, and uncheck “Allow the computer to turn off this device to save power.”
Update the Wi-Fi driver. Get the latest driver from the computer maker's support site, since Windows Update often lags behind on Wi-Fi drivers.
Forget the network and reconnect. A corrupted saved profile can cause repeated drops, so remove it in Manage known networks and connect again.
Change the Wi-Fi channel. If neighbours' networks crowd the same channel, the connection suffers. In the router settings, pick a less busy channel with the Wi-Fi channel planner, or let the router choose automatically.
Avoid so-called Wi-Fi booster apps and driver updater tools that promise to fix drops. They rarely help and are a common source of unwanted software.
If it still happens
If the drops happen on every network, not just at home, the adapter or its driver is the likely cause, so reinstall the driver or test with a USB Wi-Fi adapter. If only one network drops and other devices on it are stable, check the router's firmware and its placement.
Common questions
Why does Wi-Fi disconnect when the laptop goes to sleep? Windows may be turning the adapter off to save power. Uncheck the power saving option in the adapter's Device Manager properties, and check the power plan settings for wireless adapter power saving.
Can too many devices cause Wi-Fi to disconnect? Yes, on older or basic routers. Each connected device uses router resources, and an overloaded router can drop clients. Restarting the router and disconnecting unused devices helps.