The basics
I was undoing some of the changes I had temporarily made to my network earlier today, and at the end I was having issues with communicating to one particular device. After I bit of head scratching (it should be working), I thought about plugging it directly into the modem. So I went over to the device and saw this.
The observant among you will have spotted the issue as quickly as I did...... the cable wasn't plug in properly. This is what it should have looked like.
This is good reminder to always check the basics, is it on, are all the cables plugged in.