title: ESP8266 error when compiling: TCP_MSS must be defined
body: <p>I'm just beginning with Arduino and ESP8266. After doing some basic things with an arduino board, some leds and sensors, I wanted to replicate them over a Mini-NodeMcu Lua WiFi-Board based on ESP-8266-12E and everything went fine. Then I wanted to try WiFi connection with this board but I cannot compile any example code, all of them compile with errors as soon as I include the ESP8266WiFi.h library.</p>
  
  <p>Errors shown are:</p>
  
  <pre><code>#error TCP_MSS must be defined
  #error LWIP_IPV6 must be defined
  #error LWIP_FEATURES must be defined
  #error LWIP_OPEN_SRC must be defined
  </code></pre>
  
  <p>I can't find any info on these errors. I'm using Arduino IDE and everything is updated to latest versions.</p>
  
  <p>Thanks!</p>