@Ruebezahl_001 

You could either set static IP address on your client devices, or configure address reserveration on the router.

Address reservation is a feature that allows you to assign a specific IP address to a particular device (identified by its MAC address) on your local network. This can be useful in scenarios where you want to set up port forwarding or simply keep track of a particular device's IP address.

You should be able to see the Address Reservation settings on Advanced -> Network -> LAN Settings page.

For more detailed configuration guide, please refer to this FAQ: https://www.tp-link.com/support/faq/1657/