wifi-dethrash: Finding and Fixing WiFi Mesh Thrashing on OpenWrt

Fri, 03 Apr 2026 00:00:00 +0000

It started with WiFi presence detection. I had built a system that tracks which room everyone is in by scraping RSSI from my OpenWrt APs. It worked — but the room assignments kept flickering. Kitchen. Office. Kitchen. Office. Three times in ten seconds. The state machine was fine. The WiFi wasn’t.

My home network runs six OpenWrt APs across three floors, two SSIDs — Mercury on 5 GHz, Saturn on 2.4 GHz — all backed by 802.11r for fast roaming. From the outside, it looks like a proper mesh. From the inside, one phone was bouncing between access points 129 times in 24 hours.

I didn’t know this until I built the tool to see it.

Each row is a WiFi client, the color shows which AP it’s connected to. Healthy clients show long solid bars. Sick ones look like barber poles. See sara-iphone? That rainbow stripe is 129 connects in 24 hours — the phone is walking through an overlap zone between two APs where both have roughly equal (and terrible) signal.

The Problem You Can’t See

WiFi roaming is invisible. Your phone shows full bars, Netflix buffers for a moment, and you blame the internet. But what actually happened is your phone disconnected from one AP, scanned for alternatives, picked another one with a marginally different signal, associated, authenticated, and started streaming again — all in under a second if 802.11r is working, several seconds if it’s not.

Do this 15 times in 2 minutes between two APs that both have garbage signal, and you get what I call thrashing: rapid, pointless AP bouncing that kills throughput and wastes airtime.

Lua on Marcello Barnaba

wifi-dethrash: Finding and Fixing WiFi Mesh Thrashing on OpenWrt

The Problem You Can’t See