The solution
In a September 2020 Ars Technica report, a village of 400 residents in Wales, Aberhosan, suffered 18 months of DSL outages each morning at 7am. Openreach, a BT subsidiary, replaced old cables, but that did not resolve it.
As a final test, engineer Michael Jones says the team suspected SHINE (Single High-level Impulse Noise), electrical interference emitted by an appliance. Using a spectrum analyzer they walked up and down the village in torrential rain at 6am. At 7am, 'like clockwork', the device picked up a large burst of interference traced to one property, where the occupant switched on an old TV every morning.
The resident was mortified and agreed not to use the TV again, and the broadband returned to normal. Ars notes DSL is susceptible to interference from CRT TVs and other devices, and that Openreach reportedly planned to connect the village to fibre later in the year.
Why it worked
The outage happened at the same time every day, suggesting a scheduled source.
Replacing cables ruled out the line itself.
Impulse noise from appliances can disturb DSL on copper lines.
What can be applied
When a fault is perfectly timed, match the pattern: measure at that moment and follow the signal instead of replacing parts.
Aftermath
Broadband returned to normal after the resident stopped using the TV. Ars could not say how long each outage lasted or why one house disrupted the whole village, and said fibre could prevent future problems.
FOLLOW THE EVIDENCE