Raspberry Pi restarting intermittently

It seems that my Raspberri Pi (web server) is restarting intermittently, I haven’t been able to lock down a pattern yet? I have read other posts that this could be a power issue so I have it powered via a 2.1A 5V power supply.

I have a RaspPi 3 model B which in turn powers the BrewPi Spark Photon v2. Should I be powering the BrewPi Spark via the 12V plug as well (each independently powered)? This is extremely frustrating.

Here are some answers that were lost in the server outage:

The Pi 3 ships with the 2.5A power supply these days, although I have read the consumption is somewhere around 1.1A.

Assuming you have gone through what can be found in /var/log and ruled out a software culprit, powering the Spark externally seems like a good troubleshooting idea.

The spark does not draw much power, about 100mA.
What kind of 2.1A supply do you have? This does sound like a power issue.

sadly I purchased the item locally (I live in Korea) and I think it was the power supply…no issues after replacement…I didn’t think that was the PS (it wasn’t from China) but guess it was.