@badisensors I have this same issue and am struggling to find a consice answer to the question. Have you figured it out?

I would love to see a bit more detail about the important naming and numbering protocals for Gateways, Nodes, Sensors, and their output values within the MySensors architecture. So far, I am not finding much and progress is slow when I simply need to try different iterations and make conclusions/adjustments.

@badisensors I am also working on this. Have you figured it out? I can see my serial data from the node coming into my sensebender, but my system log says that the node is unknown and can't add it.

I'm running a MyController v 2.0 server on Rasp Pi v4. The server is setup on a DDNS so that I can send data from gateways and notes in remote locations back to the server and gain access world wide. I have had some success using the available MySensors example sketches in Adruino libraries in getting the BME680, for example, connected and transmitting data, but I am trying to add in other Adafruit boards and am getting cought up on defining the variables. As an example, I noticed that the BME680 has a gas sensor along with temp, press, and humidity. So, using the available example, I tried to create a variable for the gas value AND for the two values that are available on the CCS811 board as follows:

//create mysensors varibles, send as V_custom not as a JSON 
MyMessage temperatureMSG(TEMP_CHILD_ID, V_TEMP);
MyMessage humidityMSG(HUM_CHILD_ID, V_HUM);
MyMessage pressureMSG(BARO_CHILD_ID, V_PRESSURE);
MyMessage gasMSG(GAS_CHILD_ID, V_GAS);
MyMessage coMSG(CO_CHILD_ID, V_CO);
MyMessage tvocMSG(TVOC_CHILD_ID, V_TVOC);

But, I get the error (FYI, I cut most of the top of the compiling log believing it is not helpful here):

Using library MySensors at version 2.3.2 in folder: /Users/bjw58994/Documents/Arduino/libraries/MySensors 
Using library SPI at version 1.0 in folder: /Users/bjw58994/Library/Arduino15/packages/esp8266/hardware/esp8266/2.7.4/libraries/SPI 
Using library ESP8266WiFi at version 1.0 in folder: /Users/bjw58994/Library/Arduino15/packages/esp8266/hardware/esp8266/2.7.4/libraries/ESP8266WiFi 
Using library EEPROM at version 1.0 in folder: /Users/bjw58994/Library/Arduino15/packages/esp8266/hardware/esp8266/2.7.4/libraries/EEPROM 
Using library Wire at version 1.0 in folder: /Users/bjw58994/Library/Arduino15/packages/esp8266/hardware/esp8266/2.7.4/libraries/Wire 
Using library Adafruit Unified Sensor at version 1.1.14 in folder: /Users/bjw58994/Documents/Arduino/libraries/Adafruit_Unified_Sensor 
Using library Adafruit BME680 Library at version 2.0.4 in folder: /Users/bjw58994/Documents/Arduino/libraries/Adafruit_BME680_Library 
Using library Adafruit BusIO at version 1.15.0 in folder: /Users/bjw58994/Documents/Arduino/libraries/Adafruit_BusIO 
Using library Adafruit CCS811 Library at version 1.1.3 in folder: /Users/bjw58994/Documents/Arduino/libraries/Adafruit_CCS811_Library 
Using library RadioHead at version 1.122.1 in folder: /Users/bjw58994/Documents/Arduino/libraries/RadioHead 
exit status 1

Compilation error: 'GAS_CHILD_ID' was not declared in this scope

Ultimately, I don't understand how to define or pick a variable, I thought it was user defined, but this makes me think perhaps they are already defined in a library somewhere. Any help in directing me to either the correct structure/sytax of the variables or the location they are defined would be great. Thanks!

Re: Building a WiFi Gateway using ESP8266
I have been able to use the example ESP8266Gateway sketch in Windows version of Arduino IDE to compile the sketch to my NodeMCU. This was possible by downgrading my board library to an earlier version as has been suggested. Now I am getting the following error in serial monitor after entering my SSID and pwrd:

421801 TSM:FAIL:RE-INIT
421826 TSM:INIT
421853 !TSM:INIT:TSP FAIL
421880 TSM:FAIL:CNT=7
421903 TSM:FAIL:DIS
421924 TSF:TDI:TSL

I am trying to connect this gateway to MyController Server on the same Wifi network before adding sensors on other nodes. Ultimately, this will be a multi-node weather station that can report various conditions from nodes placed across a 300+ acre plot of land. I am relatively new to all of this, including arduino and need some help. Thanks in advance.