@Kloveless 

If the model of your router is the Archer AX1800, likely your firmware is old.

You can grab the latest version here: https://www.tp-link.com/us/support/download/archer-ax1800/#Firmware

@Tony the admin password does not work to move through the firmware upgrade. I also downloaded a firmware update when I first connect to the router.

@Kloveless 

The latest firmware added OneMesh:

If you are not able to log into your router, you may need to factory reset it by holding the reset button for 15 seconds.

Once you are able to log in, you can see find the OneMesh menu here:

@Kloveless 

My AX1800

Firmware Version:

1.2.0 Build 20201023 rel.69937(5553)

But it still does not support Mesh, see the photo. How can I get my router get mesh? Thanks.