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Guide to tracking down broadband interference
Monday 16 December 2013 17:59:49 by Andrew Ferguson

Christmas is almost upon us and by now almost everyone will have their full complement of Christmas lights switched on and that may also mean people are mumbling into their festive jumper about how slow their broadband is. A common reason for this can be that your Christmas lights may be interfering with the ADSL/ADSL2+ broadband connection.

The video below should help you to identify if your Christmas lights or some other electrical device is the source of noise affecting your broadband speed.

We also have a Broadband Interference Guide that should feature as a must read for anyone who is finding that their broadband performance is worse now we are into the long dark winter nights.

The moral from this tale of Christmas is to keep your broadband modem away from your Christmas lights and don't simply assume that video buffering or intermittent broadband issues are a problem with the line or the Internet as a whole.


Posted by Apilar over 3 years ago
Merry Christmas Andrew!
Posted by cyberdoyle over 3 years ago
Thanks Andrew, very clear illustration of the problems with wifi. Does the same thing happen if you are only using ethernet from your router? I am guessing the answer is no, but I am not techy so maybe others may be thinking the same question?
Hope you have a lovely Christmas
Posted by andrew (Favicon staff member) over 3 years ago
Actually nothing to do with Wi-Fi, AM frequencies are the ones that ADSL/ADSL2+ use, and the pops, whistles and other noise are what can play havoc for some people.

Wi-Fi is at 2.4GHz and 5GHz and a totally set of rules for RF at those frequencies.
Posted by dustofnations over 3 years ago
Although microwave ovens (whilst running) are notorious for whacking 2.4GHz WiFi connections.
Posted by joe_pineapples over 3 years ago
To get this right, if I find something giving out that interference, as long as its 2 meters minimum distance from the router, it shouldn't be a problem?. Also wondered if interference through the mains supply can finds way back to the router, via using homeplugs?.

Posted by andrew (Favicon staff member) over 3 years ago
Given a couple of meters you should be ok alas with rf it is a case of try it out to be sure.

On mains borne hopefully the modem has reasonable filter in its own power circuitry to stop this
Posted by zyborg47 over 3 years ago
Neighbours lights outside used to cause havoc with my ADSL.
Posted by Bob_s2 over 3 years ago
Highly unlikely they would need to be very close to the BT cable to have any affect. The interference is going to be low frequency so outside of Broadband range and its is highly unlkely any harmonic would affect it

The real problem is BT lines are being used way outside of there original design intent and as they are not screened can very easily pick up any noise
Posted by joe_pineapples over 3 years ago
Thanks Andrew
Posted by andrew (Favicon staff member) over 3 years ago

Can I suggest you look at the frequencies that ADSL and ADSL2+ operate at and the AM radio frequencies.

So noise a radio picks up may well be the issue, in the same way that an AM radio station causes some bins to be totally ignored.
Posted by zyborg47 over 3 years ago
@Bob_s2, I tell you now it did play hell and with others as well, because when they did not switch them on, all was fine.

Looking outside now they are off, I don't know why they bother with them since they are off more than on.
Maybe they cause problems with their own broadband
Posted by Bob_s2 over 3 years ago
The real problem is the BT lines. They are being used well outside the limits of what they were designed and are not insulated which means any electrical noise around can be picked up. It does not mean the equipment generating the noise is faulty. All electrical equipment used in the UK should be approved to the relevant CE directive(s) and should carry the CE mark.

If such approved equipment does interfere with a BT line and it is no faulty the onus is on BT to deal with their equipment.
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