DS3231 questions and time accuracy

Yes, that all looks a bit confusing. It seems that daylight saving couldn't be turned off with that JS module.

I've just made some changes to the module for you - but I don't have anything here to test with.

Please can you try:

var rtc = require("DS3231").connect(I2C1, {
  DST : false  // don't make UK daylight saving changes automatically
});

And hopefully that'll solve the problems for you