ControlD links your IPs automatically when you interact with the website OR when you use DoH/DoT. It will work in parallel from your home IP using legacy DNS, your phone using DoT on cellular, and your roaming laptop using DoH on a random hotspot. In cases of your IP changing on your home network, and you're forced to use Legacy DNS because there is no support for DoH/DoT, what you can do is configure DoH directly in the browser that you use on this network, or something that generates DNS traffic. If your IP suddenly changes, the DoH/DoT query from your home network will authorize your IP to use Legacy DNS. This eliminates the need for Dynamic DNS setups using 3rd party services.