Hello,
thank you for your reply!

I searched for the IP addresses on the second hop (they change) and it says they are within the private network. I have completely changed the router and all the cables. Is the NBN box on the wall inside my house considered part of my private network, or is that the start of the ISP's? What about the one attached to the outside of the house?

The issues occur on any device that is connected to the network. Mobiles will stop loading pages, a console will start buffering Netflix etc.

I have started all those traces this morning (I'm in Australia) and will see where we're at in 24 hours or so for me to share the results