When you change the WiFi password and (or) forgot the WiFi password, in these cases, you need to reset the WiFi router. Or if the WiFi has problems, the connection is not stable, you can also apply the way to reset the WiFi router.
Follow 2 ways bellow to hard reset TP-Link WiFi router in list devices : AX11000, AX6000, AX3000, AX1500, AC5400, AC2300, AC1900, AC1750, AC1200, AC1350, AC750, TL-WR841N, TL-WR840N, TL-WR740N, TL-WR940N, TL-WA901ND, TL-WA801ND, TL-WR1043ND, TL-WR702N.
Method 1: Reset button on WiFi router
First of all, find the correct reset button on your WiFi router. Often with TP Link will be located in the array of modem ports. Use a small pointed object and then press and hold the reset button for about 10 seconds, when the lights are on at the same time, then release your hand and wait for restart.
Method 2: Reset on modem configuration page
Make sure the router is turned on before proceeding with a reboot.
The default login IP address is 192.168.1.1 and 192.168.0.1, or http://tplinklogin.net/
The default the username and password are both set as admin.
Access the modem configuration page, TP-Link WiFi router and log in to your account.
Log in to the modem configuration page
Access System Tools> Reboot> Reboot and click Reboot button to reset your router Wifi TP Link .
In case you want to clear all settings and reset the TP Link router back to the original state as when you first bought it, click Factory Defaults> Restore to reboot and reset the TP Link router.
Thus, after resetting the TP Link WiFi router, all problems, or forgetting the WiFi password will be solved, the modem will return to its default state. You can now change the WiFi password if you want.