Good day P
Trust you are well:)
I have included the steps below as well as the link if for referencing.
How to replace your router with an AirPort Express, AirPort Extreme, or Time Capsule
- Plug in your new AirPort next to your old router. Don't move any wires just yet.
- On your iPhone, open Settings > Wi-Fi and wait until you see the Set Up New AirPort Base Station field below Choose a Network.
- Tap on the new AirPort to join it. Once connected, it will automatically offer to extend your current network. Tap Other Options and then tap Next to proceed.
- Select Replace an Existing Device.
- Choose whether the existing device is an older AirPort or a non-Apple router and press Next.
- Select the Wi-Fi network your AirPort is replacing and enter its password, if necessary.
- Your AirPort will then copy over that station's settings. Once finished, it will prompt you to switch over any Ethernet wires you had connected to the old router.
And with that, you're done! Feel free to get rid of your old base station, or move it to another part of your house to extend your network.