Hi @Gnome 
That’s totally possible via the MQTT module! (However, it will be over a wireless network then)
I’d recommend buying a small ESP8266 (Example: AZDelivery NodeMCU Lolin V3 Module ESP8266 (ESP-12F), Carte de développement Development Board Wi-FI avec CH340, NodeMCU V3 Wireless Compatible avec Arduino incluant Un Ebook! : Amazon.fr: Informatique)
It’s a small board equipped with Wi‑Fi that you can program in C using the Arduino software and that can connect to an MQTT broker.
It’s a setup I’ve already done in the past and it works perfectly:
I had written an article for the magazine « Programmez » and they put the code online here: Un capteur température/humidité DIY avec un ESP8266, du MQTT et Gladys Assistant
If you want to do this wired, you’d need to find an Arduino with an Ethernet port (they exist), and do the same