The FRITZ!Repeater (Mesh Master) only displays wireless devices in the list 'Known Wireless Devices in the Wi-Fi Network' under 'Wi-Fi > Wi-Fi Network' as connected if they are directly connected to the Mesh Master. Wireless devices that are connected to a Mesh Repeater (for example additional FRITZ!Repeaters) are not displayed in this list or displayed as not connected.

You can find an overview of all of the devices that are connected to the Mesh Master or a Mesh Repeater under 'Home Network > Mesh' in the Mesh Overview of the FRITZ!Repeater (Mesh Master).