WiFi Configuration using node.conf in ESP8266

[Jakob-B]

In some cases, it might be useful to have different wifi configurations for a node within a system. Meaning, this node does not use the wifi configuration of system.conf, but in node.conf. For example if multiple AP in a building have different credentials. However, using node.conf to set different wifi credentials, does not change <node>/build/src/wifi-config.h. This still uses the credentials from system.conf, at least for ESP8266.