An Ethernet cable between mesh units can improve the path carrying traffic between them. The cable must fit the network's operating mode, however. Before adding it, record which Deco is the main unit and whether the system is in Router or Access Point mode.

Label the existing internet uplink and any switch connections. Photograph the physical arrangement for your own records without exposing passwords or account information. A clear cable map makes it possible to restore the original layout if the new path behaves unexpectedly.

Follow the correct side of the gateway

TP-Link's Deco guidance says to establish the units in the same Deco network before adding the backhaul cables. In Router mode, satellite units belong behind the main Deco's LAN side, directly or through a switch connected there. Connecting a satellite on the upstream side does not follow that topology.

In Access Point mode, the existing main router handles routing, and TP-Link permits satellite connections to that router or other Deco units. Check the exact model and port roles, including any port assigned to a provider-specific service, before inserting a cable.

Confirm the actual connection type

After the planned change, inspect the satellite in the Deco app's network map. Verify that the intended wired connection is reported, then test ordinary traffic through that satellite. A cable being plugged in is not sufficient evidence that it became the backhaul path.

You can wire only the units that have suitable cabling and leave others wireless. Avoid general claims that every model uses wired and wireless paths identically; advanced aggregation features and firmware can change that behaviour.

If the path works directly but becomes unstable through a switch, preserve that comparison for support. Check the switch's compatibility and configuration instead of disabling network-loop protection indiscriminately. Finish with a diagram showing the working ports, the app's connection result and the client task tested through the satellite.

References: TP-Link Deco Ethernet backhaul.