@Electroren , You are redirecting this port to 192.168.0.66. What kind of WIFI device is the IP 192.168.0.66? It looks like a router. If you run a router with this IP, you have a double NAT in use, which can lead to problems. Please describe exactly what you want to do with the port forwarding.
This is an arduino ESP8266 wifi module that I have programmed miself. It just shown an HTML page with datas it measures from my heating system and that I whant to consult from abroad.