Best posts made by rb3rg

Yes, I can confirm its working..
in the GatewayESP8266 make sure to change from this:

#if defined(MY_USE_UDP)
  #include <WiFiUdp.h>
#else
  #include <ESP8266WiFi.h>
#endif

to

  #include <WiFiUdp.h>
  #include <ESP8266WiFi.h>

You have to have both libraries instead of just one (wiFiUdp.h)
For case sensitive systems (Linux, OS X) also you have to have the correct upper/lower case in the library name.. it must be:

#include <WiFiUdp.h> 

and NOT:

#include <WiFiUDP.h> 

as in the the example mysensors file.

Scenario: GatewayESP8266 with UDP

If you clone the development version from github and try to compile the GatewayESP8266 with MY_USE_UDP it will fall over a bunch of compilation errors.
The reason is found in the MySensors.h around line 153, GATEWAY - TRANSPORT

#if (defined(MY_CONTROLLER_IP_ADDRESS) || defined(MY_CONTROLLER_URL_ADDRESS))
	#define MY_GATEWAY_CLIENT_MODE
#endif
#if defined(MY_USE_UDP) && !defined(MY_GATEWAY_CLIENT_MODE)
	#error You must specify MY_CONTROLLER_IP_ADDRESS or MY_CONTROLLER_URL_ADDRESS for UDP
#endif

Once you define MY_USE_UDP you will also want to define MY_CONTROLLER_IP_ADDRESS to send the packages to your controller,
However as you see in the first line if MY_CONTROLLER_IP_ADDRESS is defined then MY_GATEWAY_CLIENT_MODE will be auto defined and this
will conflict with UDP use.

I've fixed it changing to:

#if (defined(MY_CONTROLLER_IP_ADDRESS) || defined(MY_CONTROLLER_URL_ADDRESS)) && !defined(MY_USE_UDP)
	#define MY_GATEWAY_CLIENT_MODE
#endif
#if defined(MY_USE_UDP) && (!defined(MY_CONTROLLER_IP_ADDRESS) && !defined(MY_CONTROLLER_URL_ADDRESS))
	#error You must specify MY_CONTROLLER_IP_ADDRESS or MY_CONTROLLER_URL_ADDRESS for UDP
#endif