In that case, Openreach, have a few systems that can be used to show its evidence in a location, but not to pinpoint it. That requires good old fashioned legwork.
Reminds me of a problem I had with ADSL when I lived in a different village many years ago.....
I noticed the SNR dropping from 8dB to 1dB at regular intervals for up to an hour at a time, then returning to perfect levels. The ISP were helpful and checked everything out - no fault found. This drop was being handled so well by the OR adaptive kit at the exchange that the connection never dropped, but of course the speed was lower than it could be.
I went into detective mode over the course of a week……
What could be the source of the interference? Sure enough with a SW radio I could clearly hear the interference (coinciding with the drop in SNR), but where was it coming from? Street lights? No. Neighbours? No. My equipment? No. Over two weeks my net widened, with considerable 'leg work'....
Eventually I went for a long walk and stumbled across a sewage processing plant over two miles from my property and that of any other village property. I noticed the plant machinery ran to roughly the same timing. I returned the next day, armed with my laptop, VPN connected to the live SNR output of the modem, the SW radio and a six pack of beer, and made myself comfortable on the grass by the fence outside the site. With only one can of beer (maybe two / three...) down - Bingo - as soon as the machinery started up, the SNR went down to almost zero and the radio nearly blew my ears off with the noise! When it stopped the SNR went up by at least 6dB.
I contacted the sewage processing company, who to my surprise, were very helpful and quickly setup a site visit. I showed the Engineer my data, both historic and live, and we went inside the plant control room.
I will never forget the look of horror on his face when he discovered that the racks had never been Earthed since installation - there was the fault! Ironically, he even said that they wondered why in the office, their ADSL connection to the plant dropped out when the machinery ran.
A couple of weeks later, the problem went away, for not just me, but everyone in the village (about 500 properties), most of whom were probably unaware.
So the moral of this story? To find interference often requires time, a SW radio and as Zarjaz says 'leg work' (and, perhaps, a six pack of beer....:-))
Mendip.
Edited by deleted (Tue 22-Sep-20 15:34:08)