board manager will not list Generic ESP8266 module on IDE 1.8.3 File, Preferences, Settings, Additional Board Manager URL contains http://arduino.esp8266.com/stable/package_exp8266com_index.json So what could be wrong ?
Please try this:
- Tools > Board > Boards Manager
- Wait for downloads to complete
- Scroll down until you see the "esp8266 by ESP8266 Community" entry. Click on it.
- Click "Install".
- Wait for installation to complete.
- Click "Close"
The ESP8266 boards should now show up in the Tools > Board menu