@PW78 

Hi, Welcome to the community.

Is the current network topology like this:

internet---modem router----switch------Main Deco M4

                                                     \-----Satellite Deco M4

                                                     \-----Other LAN devices

And Does Deco M4 work in the wireless router mode?

If yes, it is suggested to change Deco into Access Point mode:

How to set up Deco to work in Access Point mode

Thank you very much.

Best regards.