Open the configuration website of your TP-Link wifi router, go to Advanced → Wireless → Wireless Settings and configure the following:
The selected Password will be your wifi password for connecting other devices with the router!
Reboot the wifi router to activate all changes.
After reboot, change the wifi settings on your devices (computer/smart phone/tablet …) to the new set-up 5 GHz network.
To reduce the risk of changing back to the 2.4 GHz network, delete the 2.4 GHz wifi network settings.