Can't connect to this network, explained and fixed
Windows shows the message “Can’t connect to this network” when it tries to join a Wi-Fi network and the connection fails. The message itself does not say why, but the usual causes are a corrupted saved network profile, a wrong or changed password, or a damaged TCP/IP or Winsock stack.
The fix, in order
Forget the network and reconnect. Go to Settings, Network and internet, Wi-Fi, Manage known networks, select the network, choose Forget, then select the network again and enter the current password carefully.
Run the Network troubleshooter. On Windows 11, open the Get Help app and run the Network and Internet troubleshooter; on Windows 10, Settings, Update and Security, Troubleshoot, Network Adapter.
Restart the device and the router. A hung adapter or router state is a common cause, and a restart clears both.
Reset the network stack. Open Command Prompt as administrator and run netsh winsock reset and netsh int ip reset, then restart the computer.
Reinstall the Wi-Fi driver. In Device Manager, expand Network adapters, right-click the wireless adapter, choose Uninstall device, then restart. Windows reinstalls the driver on boot. If it still fails, install the latest driver from the computer maker's support site.
Use Network reset as a last step. Settings, Network and internet, Advanced network settings, Network reset removes all adapters and returns networking to defaults, so you will need to reconnect to Wi-Fi afterwards.
Only download Wi-Fi drivers from the computer or adapter maker's official support site. Driver download portals and driver updater tools are a common source of malware.
If it still happens
If the network works on other devices but this PC still cannot join after a network reset, check that the router's security type matches what the adapter supports, and try connecting to a different network to prove whether the fault is the PC or the router. A PC that cannot join any network has a driver or hardware problem.
Common questions
What does “Can't connect to this network” mean? It means Windows tried to join the network and the attempt failed. It does not identify the cause on its own, so work through the steps in order: saved profile, password, troubleshooter, stack reset, driver.
Why did it work yesterday and fail today? The usual triggers are a router password change, a router firmware update, a Windows update that replaced the Wi-Fi driver, or a corrupted saved network profile. Forgetting the network and reconnecting fixes most of these.