I have some Deco m9+ mesh routers. When I visit the IP of one of them using my web browser, I can login on the device locally.
If your X20’s work the same, this way you can check if the IP is valid.
When you reach the local login, test your password here. In my case it’s the same as my TP-link cloud account, but I don’t remember if this is default or that I just did this on purpose.
When you have the IP and the password, you can use this credentials to add them to your Homey.