@Ale98 

Hi, welcome to the community.

Regardless of the cable length, your network topology would be perfect.

But 50 meters long cable would be a challenge for Ethernet Backhaul and it needs to be a high-quality Ethernet cable.

For your situation, Deco is not your only choice and  2* standard Access Points, like TL-WA1201, might be better:

https://www.tp-link.com/en/home-networking/access-point/tl-wa1201/

Thank you very much.

Best regards.

  @Ale98 

Hi, Thanks for getting back to me.

The satellite Deco gets signals from the main Deco via Mesh Backhaul. When the Mesh Backhaul is based on an Ethernet cable, it is normally called an Ethernet Backhaul.  The Ethernet Backhaul of Deco is based on another standard IEEE 1905.1 protocol. During the transmission of packets, longer cables tend to experience more signal loss and interference. If the normal network data is reduced, you might have poor bandwidth or an unstable connection. So if it is a laptop or standard access point, its speed might be less expected but you could still have internet. While for Deco, if the Ethernet Backhaul data is reduced or barely received by Deco, it might try to seek Mesh Backhaul via Wi-Fi, which is also not possible due to the long distance. Then satellite Deco would fail to connect to the main Deco to obtain an internet connection.

We have also received user feedback that Ethernet Backhaul failed with a 30 meters cable but in the Lab test, the engineers were able to have Ethernet Backhaul via 100 meters cable. Since the Cables vary and it is hard to test the quality, a long cable is usually not suggested.

For TL-WA1201, though it does not support mesh, it would not initially suggest clients roam to the closest access points. While due to the long distance, clients themselves could abandon the access point that could barely hold a decent signal. And if the garage devices did not move around, they would directly connect to a stronger Wi-Fi.

Thank you very much.

best regards.