I have been using a NodeMCU V0.9 in a project for years now. Recently one parameter needed some tuning, but after uploading the changed sketch ESP8266Ping from https://github.com/dancol90/ESP8266Ping returned wrong results (pinged server is allegedly offline which is not true).
The 'ping part' of the sketch has nothing to do with the made change and even the sketch version without the change did not work anymore. Long story short, went back to 3.0.2 as before and it works like a charm.
Just to let you know, cause it was a huge waste of time to find the cause due to so many related things ...
