For a couple of years now I have a network device in my place, called “Whitebox” by SamKnows. It is part of the following endeavor:
Together, the European Commission and SamKnows aim to provide Europe with reliable and accurate statistics of broadband performance across Europe.
Volunteers will receive a purpose-built broadband measurement unit which can be plugged into the existing modem/router. This is called the SamKnows Whitebox.
The network device periodically performs measurements without interfering with actual payload traffic in your network. It monitors Ethernet as well as wireless LAN. The data becomes uploaded, aggregated, and nicely visualized in a personalized dashboard.
If you are paranoid, you probably do not want to have such a device in your home and you might argue that you can measure for yourself. However, I think that this project is trust-able and the statistics obtained by SamKnows are essential for evaluating and developing broadband Internet access in Europe. Furthermore, the data obtained by my Whitebox were already multiple times useful for convincing my ISP that it is not holding up its end of the contract.
I recommend signing up: https://www.samknows.eu/sign-up/