I tried including src/system_network_internal.h so I could build my own wrapper class around WiFiNetworkInterface but I then got build errors stating that variables defined in inc/system_network_internal.h are not defined. I noticed these two files have the same guard of:
#ifndef SYSTEM_NETWORK_INTERNAL_H
#define SYSTEM_NETWORK_INTERNAL_H
So now I see they can’t both be included… what is the difference between these two files?