@Goonermel 

Hello, please check below if you cannot find the M4 when logged in on another phone:

1. Check if you've logged in the correct cloud account which your Deco M4s linked to. Try to log out and log in again.

2. On the top-middle of the Deco app, please check if you can see any Deco network you've created on the previous phone.

3. Reboot the Deco network, and then connect the phone to the main Deco's Wi-Fi network.

4. Try with another phone.

Thanks.

@TP-Link_Deco 

Did you get your new phone to work with old setup? 

Have the same problem with my new phone. 

@JeffreyT 

Hi, yes and you need to make sure that you have logged into the same email account on the new phone;

--if you have already done that and it still required a new setup, please leave me a private message with the following information:

1. your TP-Link ID for the Deco;

2. the MAC address of the main Deco;

Thank you very much.