Great. I have wifi, so I will use the esp8266. I think I will continue with this board here as it's something I can find in a local store nearby.

I just need one more clarification though: in the ESP8266 gateway page I see the following paragraph:

Just connect the radio, install gateway software and you're good to go.

Now, considering that the board already has WIFI, why do I need the radio ?

Perfect. It's clean now. (an MQTT gateway is what I need too)

One more question: what kind of radio are you using ? The tutorial page for the ethernet gateway mentions RF24, but I understood from other members in the forum (example) that the RF24 doesn't have a very strong signal and that I should use RFM69 instead. However, since I'm a noob on this part, I'm not sure if it's so easy to replace one component with the other.

Does this mean that I don't need a gateway at all ? Or you meant that I don't necessarily need an mqtt gateway in particular ?

That's a good question. I didn't realize that the arduino board is not specified (neither in this tutorial nor in the ethernet one).
However, I see that the ethernet gateway project (https://www.mysensors.org/build/ethernet_gateway) mentions that any arduino board would be fine. Since I'm only a beginner, I don't know what board would suffice for this kind of project. Could you recommend me the cheapest Arduino board that can do the job ?

Hi, is there any case for this gateway ? I wouldn't want all those wires to lay around in plain view..

Hi,
I noticed this tutorial here and I don't really understand how all these components work together and what's their role.

Could anybody explain ? A diagram would help tremendously, if there is one..