Comment by Twirrim

From a slightly more old-school sysadmin approach, I learned to troubleshoot roughly in line with the OSI model (https://www.lifewire.com/layers-of-the-osi-model-illustrated...), starting at layer 1 (physical) and working up.

That's not to say I spend a whole lot of time looking at the lower levels, but my quick mental checklist starts off down at physical points, and I try to quickly eliminate possibilities. In a lot of cases it's obvious it's a code / logic bug, and you can completely skip the lower layer stuff, but making it a conscious step pays off.