@Supperouge I think what you have is Deco X50-5G. In Deco app, open Update Deco and check what model name it shows there for your Deco unit. If this is what you have, the best Satellite (additional)...

@EdoM Easymesh systems are not compatible with Deco mesh systems. If you want to keep x50-4g, you may wish to return TL-WPA7817 kit and look for different options.

@Randomcdn If you have Ethernet port in that room, which is connected to the rest of your home LAN, there is another option. Get the most inexpensive 2.4GHz WiFi router you could find. In my region...

@R-ehv This variation of Deco M4 does not support Connection Preference feature with its current version of firmware. It appears you purchased the whole set from one place, all three units are the...

@R-ehv This feature is not available in some Deco models. For M4, it is even more complex: some M4 variants have that feature and some don't. Usually, this feature availability can be established...

@kes1962 You should be able to connect Deco units directly to ISP router. Most ISP routers support Deco Ethernet backhaul. In a very rare chance yours does not, you may need to get TP-Link gigabit...