Hi, I was hoping if some of you could help me out with a problem I seem to be having.
About a month ago, I signed up for the co-op phone & broadband's ADSL2+ service. Prior to this I was on Plusnet VDSL2 (40/20) and just before that Plusnet ADSL - this was from a property transfer where I had Plusnet there; in the previous property I was on a Market 2 exchange and had an ADSL2+ service with them, while in my current property the standard BT Wholesale ADSL is ADSL1 only (though Plusnet did hold my Market 2 price rate until I did switch to VDSL2 with them).
When I initially moved in to my current home, the Plusnet ADSL download speed was "only" 6.5 to 7 Mbps. Not criminal or a bog standard ADSL Max service but I suspected more could have been done. The previous occupants I suspect had a VDSL service before they left as the master socket had a BT Openreach VDSL interstitial plate. I had taken with me an ADSL Nation faceplate that I used at my previous residence but I didn't fit it in with the VDSL plate already in place, instead I hardwired using a krone punch down tool a cheap telephone extension cable to the landline phone at connections 2 & 5 and used a roughly 3 metre long cw1308 cable to connect B & A to the modem I was using. Phone line was clear, and ADSL speed was no different from the test socket, so was was seemingly fine with pretty consistent performance.
When in mid-2014 Plusnet raised their prices I was able to haggle a deal of them for VDSL broadband for an 18 month contract at a reduced rate. There really wasn't any need much for a BT technician to come around to my house other than to deliver the (ECI) VDSL2 modem, but he insisted in providing an extension of the master socket to where the previous ADSL modem was (Plusnet sent out a new router compatible with the service, their TG582n) where he cheekily reused the cw1308 cable I had as a xDSL extension! Speed tests never led up any higher much more than 33Mbps down and 8Mbps up despite BT's checker stating that up to 60Mbps down and 12.5Mbps up was possible but I wasn't too fussed as it was more than adequate for my needs.
So with my contract up with Plusnet and the VDSL service cost now at the standard Market 1 rate, I decided to look around considering I don't live too far from my local exchange and that despite it still being a 20CN exchange, Talk Talk had unbundled it (no other LLU operator though) I settled on the Co-op phone & broadband service as they were a Talk Talk network reseller. In saying that, the speeds being returned for my line were being given as low as 3.1Mbps down which seemed strange given the prior ADSL service on the line, but as long as an upload of roughly 1Mbps was obtained I didn't plan to be too worried.
So on the day of the changeover the Plusnet connection went down at 12:01 AM. In the morning I took out the VDSL ECI modem and Plusnet router and in its place a TP-Link TD-W8968 ADSL2+ modem whose user details were filled in from a letter the co-op sent me. The ADSL2+ service went live at around 11:30AM but from checking the router stats things looked slightly disappointing - the downstream attenuation was only 28db but the corresponding SNR margin was 12db and the speed was only 7.5Mbps. I though OK, the line likely needs trained anyway, and the upload speed connected at 950kbps. However in the early evening I noticed that the SNR fell down to just 3.1db, recovering shortly after midnight. Some brief testing with different modems showed that when the SNR fell, attempting to reconnect with the DSLAM meant reconnecting at a download speed of 5Mbps or even less though with an SNR of 12db - the exception was the TD-W8968 where if it was forced to reconnect it was able to hold on to speeds of around 6Mbps. I decided to leave in the previous Plusnet supplied router for their VDSL service which I'd now reconfigured for ADSL2+ and left it alone for a week. The following patterns were noticed...
* The sudden drop in the SNR occurs around 4.30pm to 5.30pm on weekdays until around midnight to 1.00am. At weekends the interference can come in much earlier in the day, usually around lunch time. I've done tests where I've had no other mains electric equipment in my home running other than the modem/router & the fridge with the former connected to the BT test socket, and there was no difference in the presence of the different SNR peaks so I can pretty much rule out anything in my home being responsible, including my heating and hot water timers.
* I've used the Plusnet TG582n in ADSL mode, the TP-Link TD-W8968 and an old Cable & Wireless ADSL2+ modem/router - of the three the TG582n gives the highest download sync speed at 8.2Mbps marginally ahead of the C&W, but was dropping the connection during the evening when the SNR ratio fell to 3-4db and was resyncing at around 4.8Mbps down with a 12db SNR. When the cause of the SNR drop disappears in the early hours of the morning, the SNR then rises up to over 19db! A manual resync at this time brings the download speed back to >8Mbps with a 12db SNR, until the interfering source comes again. During the period when the interference is present, the FEC errors for both download and upload skyrocket.
* Interestingly, during the times the download SNR drops, the upload SNR and speed is barely affected.
* I got my hands on an old BT Business Hub (2wire 2700hgv, came with the latest firmware so I couldn't really do much about that) and managed to get it set up for my line despite it being a little hassle when it comes to the MTU settings. It's upload speed connection is consistently 1Mbps, but even it has struggled to hold on to an 8Mbps download speed when the interference hits the download SNR margin when it falls to 4db or lower and a couple of times this week it has lost sync, resyncing at just over 5Mbps when it does.
I've came to the conclusion that I have a REIN problem. Where I live is a village in County Tyrone in a small housing estate next to a small Primary school. The times this interference comes on suggests that the source is from someone who works during the day on weekdays and possibly also has children at school. AM radio interference I think can be ruled out - the nearest transmitter site (BBC Enniskillen) is about 15 miles away LOS with an ERP no greater than 1kW, though there is another transmitter in a different direction slightly further away across the border in Co. Monaghan used by Spirit Radio which is on 549kHz with an ERP of 25kW.
I've attached screenshots below from the 2700hgv settings showing as many details as possible from it. With regards to the bitloading, when it resyncs in the presence of the interference there is no bitloading above bin no. 290, and those bins in the 200s are not as high as they are when it is synced without the interference present.
But even allowing for the interference, when it isn't there the maximum download sync rate looks rather low - according to my downstream attenuation figures which tend to hover at either 28 or 29db I should be able to get close to double the download speed potentially than what I am currently getting at the best of times! Something just doesn't seem quite right, yet Talk Talk's checkers tend to give rough figures of anything between 3-12Mbps depending on the day I check and I was only "guaranteed" a 3.1Mbps download speed. I'd rather try and sort the problem out myself if I can before contacting my ISP or getting Openreach involved - I have been looking at constructing an additional filter mentioned on the
Wireless Waffle blog consisting of a choke and a low-pass filter to attenuate out-of-band signals where wideband interference could be causing my SNR drops, I'm just waiting on getting the appropriate inductors to build it as I have everything else. The drop line comes into the house via an underground duct though it's path out of here I'm not that sure of except to know which roadside cabinet it connects to.
I hope I've said plenty, I might have said too much! All help on this is appreciated.