I worked from the lake place, and my laptop found a rhythm. Approximately every five minutes, the internet was gone for approximately thirty seconds. That is long enough to kill a video call. It is short enough that the connection returns before a diagnostic tool opens. Then everything looks fine. This is the most annoying class of problem: it is intermittent, it repairs itself, and it hides when you look at it. It is the car noise that stops at the mechanic.

38 disconnects in five hours

I stopped the casual observation. I pulled the logs from the access point controller for the morning. The logs showed 38 hard disconnects in 5 hours. Each disconnect occurred on the same access point, on the same channel, and at the same weak signal level. A reconnect followed each one after five to forty seconds, to the same access point.

The laptop did not roam to better coverage. It drowned, came up for air, and swam back to the same spot.

I caught one drop live

Then I had good luck: I caught a drop live. Three parallel pings ran: to the router, to the network switch, and to a public DNS server on the internet. At 10:15:21, all three pings died at the same time. Six seconds later, the laptop reported that it had no route to any address. Twelve seconds after that, all three pings returned at the same time, and the controller logged a matched disconnect and reconnect pair.

When the router, the switch, and the internet disappear in the same instant, the problem is not one of them. The WiFi link itself collapsed. Each layer above it fell at the same time.

During the same session, a Raspberry Pi with a wired connection on the same network pinged the internet. It received 695 replies from 695 pings. There were zero gaps. The internet connection did not blink one time. I had suspicions about the ISP. This time, the ISP was innocent.

The one bad chair

The signal numbers told the real story. My desk sits at the far edge of the coverage of the nearest access point. The signal is weak, and the link collapses at intervals. Each collapse forces a full reconnection. The laptop cannot escape to the other access point, because from that exact desk the other signal is weaker.

So the laptop drops, scans the area, finds the same marginal option, and joins it again. This continues forever. Each phone and tablet in the house was fine. Those devices roam, or they sleep through the problem. The laptop was the only device attached to the one bad chair in the building.

I examined the more interesting suspects: the new WAN hardware, the firmware, band steering, power-save settings, and a scheduled job on the laptop with a five-minute interval. Each suspect was innocent. The intervals were not regular. Their average was five minutes, because random failures at a marginal signal level make that average. There was no gremlin. There was geometry.

Move the desk

Here is the fix list, in order of engineering sophistication: move the access point nearer to the desk, add a third access point, or move the desk. The last option is free. I have many years of network knowledge, and I did much log archaeology. The root cause analysis ended where each cottage argument ends: the furniture is in the wrong place.