So, I've been having intermittent packet loss for the past few days. Strangely, last night when I logged into my Super Hub's web interface, I was greeted with a Sky Hub interface with all of my devices (including wired connections) connected to it!
Tonight, I've had a bit more time to so some troubleshooting, and noticed that whilst I was doing speed tests, the speedtest-cli kept telling me I was coming through Sky's network. "Odd," I thought! So I did some more testing...
pi@raspberrypi:~$ while true; do curl v4.ifconfig.co && sleep 10; done
As you'll see, this is a very odd thing - external address changing every 10 seconds?
The 94 address is a SKY address, and the 92 is a Virgin address...
Yes, I have a powerline Netgear wifi extender that I use to extend the wifi into my loft. I disabled them that night and the problem went away. Somehow I must have been picking up a neighbor's powerline signal and routes were being injected into my network.
Very strange, since I was still connected to my SuperHub's wifi, and the raspberry pi was connected via ethernet directly through the Super Hub...
Anyway, I've factory reset those Netgears and made doubly sure they were running in Secure mode and I haven't had any issues since.