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Comment by EvanAnderson

9 hours ago

Oh, wow. This sort of happened in my life!

My grandmother's house is adjacent my parents' w/ 200 ft. between and line of sight. Back in 2013, when my grandmother moved into the then-new house, I setup a point-to-point wifi bridge between them to share my parents' Internet connection and give me easy remote support access to grandma.

Summer of 2023 visiting relatives complained the Internet service in grandma's house was slow and unreliable. There were repeated suggestions made by helpful relatives for purchasing a new WiFi router for her house, getting independent Internet service, etc.

Grandma was happy with it, and the relatives went home, so I put off looking at it. When I did finally look at it, months later (when I went over for Thanksgiving) everything seemed fine.

When the relatives came to visit in summer 2024 they complained again. I looked at it immediately and found massive packet loss on both ends.

The ornamental trees planted along the driveway between the houses were the culprit. With the leaves off (say, at Thanksgiving time) it was fine. When the relatives came to visit in the summer the trees were in full leaf and acting as very good attenuators.

The trees were newly planted when grandma moved in. I didn't even think about them getting bigger and fuller when I set up the link. They filled out in the 10 years intervening, though. (Chalk it up to me still being relatively young and not thinking about installations on 10+ year timescales when I put it up.)

Fortunately there's a room in her house with line of sight to my parents' house unobscured by trees. It meant putting the radio outside a bedroom window instead of the attic (where I'd originally stashed it), but it solved the problem and ended complaints from relatives.

For GHz signals water is a pretty good dampening material, I can tell on some links whether it is foggy!

  • Your microwave uses 2.4 GHz specifically because it's particularly well absorbed by water :)

    • A friend told me once that his mouse stops working when someone is using the microwave. His room was on the backside of the kitchen.

      When I took a look at it, it turned out that his (proprietary) wireless USB adapter for the mouse was very close to the band of the noise of the microwave. The microwave was also not properly grounded and shared a circuit breaker with his room, as apparently the kitchen was formerly larger and then split into two rooms by the landlord.

      That was quite funny seeing that problem happen in action, he was always joking about a ghost in the machine, and I was joking about him being radiated by his microwave.

      The cool part is years later in University one of my commilitones told me that his mouse stops working when the fridge turns on. The first thing that I checked was whether or not there's noise on the power circuit, et voila, easily fixed.

      4 replies →

    • This happened in my life too!

      I had a Customer complaining about bad WiFi in a conference room. Every time I checked it I had good performance. Eventually I attended the meeting most of the of the complaints related to just to observe.

      What I observed was workers from cubes near the conference room microwaving food for their lunch in the break room right across from the conference room.

    • That's a common myth. There is no special water resonance at 2.4GHz, it's just a frequency allocated for general use. Early microwave ovens didn't use 2.4GHz