The UniFi controller update reset my DNS filtering profile to “default” without a word. Twenty minutes of very confident debugging later: it was the router, and the router had told nobody.
Logical Disconnect
Where I write down how I work out what’s wrong.
Networks, electronics, code, and the occasional airport. Most of it starts with something that used to work and doesn’t any more, and ends with a sentence I wish someone had told me four hours earlier.
It updates most weeks, in four sizes.
The four sizes
Start here
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Why your Wi-Fi is fine and your DNS is not
Four commands, in order. The order is the whole article, and it is the piece people send to their families.
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Troubleshooting by smell: noticing what’s off before you know why
The useful part of experience is the flinch you get half a second before you can explain it. My best attempt at teaching that.
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What I learned building a quiz app for 200 people in a noisy room
Everything that broke was something I had already been warned about. A catalogue of ignored advice.
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The oscilloscope is not the hard part
On buying test gear you do not yet know how to use, which I recommend doing.
Lately
The whole stream-
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Troubleshooting by smell: noticing what’s off before you know why
The useful part of experience isn’t the answers, it’s the flinch you get a half-second before you can explain it. Here’s how I try to teach that.
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Spent twenty minutes convinced a switch port was dead. It was the cable, which I had personally labelled “good” in 2021. Relabelled. Trust nothing you wrote on tape five years ago.
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Fix It Shack — Swapped the puzzle grid to SVG. Instantly legible on a phone; instantly slower on a Chromebook. Two steps forward, one Chromebook back.
