Why is my ADSL line dropping despite good stats?

[dirtydog]

Can anyone explain this as, according to my understanding of ADSL, this doesn't quite make sense.

I am on MAX, and if I cap my router's sync rate I get a rock solid 1Mb speed 24/7 with minimal CRC errors/errored seconds. My SNR margin varies from around 21 during the day to 15-16 at night. I can also get 2Mb downloads during the day, but at night the SNR margin drops too low.

What I tried was capping my sync rate to 1728kbps, which is apparently enough to generate a BRAS profile of 1500kbps. If I do this during the day, my SNR margin is around 17-19. At night (now) it drops to around 9-10. But, at night it drops the connection within seconds every time. Surely an SNR margin of 9-10 should be perfectly good enough? Indeed with my old (and crap) Voyager 105 USB modem, my SNR margin used to be no higher than 9.5 during the day and it was rock solid (only during the day). So why doesn't it like it now?

All I can think of is that my line used to be interleaved, and now it's set to fast? But even so, why is the line dropping with an SNR of 9-10? If I cap the sync back to 1152, for a 1Mb speed, it's rock solid again (SNR currently 16).

It just seems that, on paper, I should definitely be able to get 1.5Mbps 24/7. But it ain't happening

 

[EnIgMa]

ok m8y this may help it may not but it sorted me out a treat

im on max and syncd at 5-7 meg but my line would drop a hell of a lot at night like 20 times, this was due to a low snr i thought but it was holding around 7-8 so should have been ok.....

my isp then put my line on interleaving which dropped my connection to 4meg which according to bt was well under my fault threshold so they switched me back to fast and it started happening again.. this went on for weeks and had a really bad connection.....

in the end i read about a trick you could do with your bt master socket... basicly if you unscrew your bt master socket you may find 6 wires connected, you only actually need 4 which are colored red and blue i belive but dont quote me on this.... the 3rd set of wires that are colored orange are called the 'ring wires' and are for basicly supplying power to old phones so they would ring.... well to cut a long story short i ripped the two orange ring wires out, that was 3 weeks ago and i have now never been disconnected and am constantly syncd at 8meg with a healthy snr of 11-15

this may not work for you but it may be worth a try, basicly with that wire connected it creats like a big radio loop which affects your line stats

have a look here might make a bit more sense

 

[dirtydog]

Yeah I've already looked at that I am using an XTE-2005 faceplate and the router is connected directly to the master socket with a short, high quality RJ11 cable designed for ADSL. There are no phone extensions at all. The router is connected to the computer via an ethernet cable.

 

[tolien]

The only difference between fast and interleaved mode is you've got more error correction in interleaved mode - it isn't going to magically make your line more stable if you aren't seeing a high error rate.

Does it improve if you reduce the sync rate, and are you sure it's actually losing sync in the first place?

 

[dirtydog]

Yes it improves if I reduce the sync rate from 1728 to 1152. I haven't tried it at any speed in-between those because it would still only give me 1Mb. Yes I am sure it is losing sync, both from the router log and from seeing the DSL light on the router going out, and then flickering until it re-syncs

edit - I have just tried using another RJ11 cable and my SNR margin has gone up to 24.0 @ 1152 (normally ~21) and 19 @ 1728 (during the day)... so maybe the cable is to blame. I won't know whether this new one will do the trick until some time after 7pm tonight though so we'll see If this doesn't work I'm gonna try connecting directly to the test socket just to rule out a fault with my faceplate filter.

 

[dirtydog]

I am now connected directly to the BT test socket, by-passing the XTE-2005 faceplate altogether, and the connection is rock solid and with an SNR margin of 13.5-14.5... so either the XTE is faulty or it just isn't very good...