@amc22004 Go to the TP Link page for your router, select the support page, then the user manual. Do a factory reset by pressing the reset button until the light flashes. follow the instructions for...

@Lee_Vinson go to advance/network/dhcp server

@Lee_Vinson Sign onto the router and go to advance/settings/system/backup and restore

@ugottobkidding If a device will not connect, delete or forget the network and then reestablish the connection

@Alan-65 It has been a while since I used an AP. Be sure all the setings are the same such as mode and security settings. Do not recall if hiding ssid makes a difference but they are handled...

@Ckenneth Is he doing it by changing the MAC address? If so, use security options and white list all your devices.