My ISP kept dropping and I had no proof, so I built something to catch it. I'm not sure the finished thing counts as show and tell, so tell me if I've got the rules wrong.

Hardware: Waveshare ESP32-S3 1.28" round touch screen in a CNC metal case. The firmware is written in Rust.

What it measures, every second:

TCP connect time to a public host on port 443

DNS lookup time

Latency to the home gateway

Wi-Fi RSSI

Why TCP and not ICMP: ICMP was quite unstable for me, with timeouts that didn't match what I saw on my laptop. TCP connect and DNS timing were much steadier and matched real outages.

The radio problem: Running Wi-Fi and Bluetooth at the same time caused artificial latency. They share one radio, so the chip has to time-slice between them. With Bluetooth on, my TCP latency measured about 60 ms. With it off, the same connection measured about 12 ms.…