I've got a Raspberry Pi 1 Model B that has been my trusty workhorse for a few years. It normally chugs away happily running transmission, pi-hole and a node.js app simultaneously.
All of a sudden it's started to become unresponsive under load. I can no longer SSH into it, but I can still ping it during this time. I can't access the transmission or pi-hole web clients when this happens either.
The only thing I can think of is that I've moved abroad and I'm now on a 120v circuit, but the power unit does say it's capable of running on 120-240v. It's a 5V 2A unit which has never caused me any problems in the UK.
What are some steps I could take to try and diagnose the problem?