Should be the router problem, you can follow the following method to set up your phone:
1. Click Settings --WLAN, select the arrow next to the name of the network you want to connect to, choose not to save the network, and re-enter the password.
2. Reboot your phone and router.
3. Still not working, I suggest you try another WIFI network to see if it can be used normally. If it can be used normally in other wifi router environments, it may be caused by the problem of the current router itself.