I'm newly registered at the forum, but I've been viewing it for a long time prior to registering.
I have a few questions about ADSL2+ as I feel as if I'm not receiving the speed I should be, and I believe that I may have an issue.
I'm currently on 21CN WBC after switching from LLU.
First off, my line has a downstream attenuation of 38.5 dB (pretty reasonable I think) though it's only sync'd at a little over 7300 kbps at 6 dB fastpath. I've listed some of my line statistics below so I don't have to explain myself (as much), though I have omitted information about errors, data transfer and uptime (I can post them if it's really required, however I feel it's not).
DSL Type: ITU-T G.992.5
Bandwidth (Up/Down) [kbps/kbps]: 1.107 / 7.335
Output Power (Up/Down) [dBm]: 12,8 / 0,0
Line Attenuation (Up/Down) [dB]: 19,2 / 38,5
SN Margin (Up/Down) [dB]: 5,9 / 6,9
System Vendor ID (Local/Remote): TMMB / ----
Chipset Vendor ID (Local/Remote): BDCM / IFTN
Before uncapping the upstream, the downstream was over 7900 kbps.
Is it true that I should be able to receive a bit more than this?
Secondly, when the telephone is unplugged, the SNR drops by around 0.3-0.5, and of course when it's plugged back in it rises again, and I've tried two different telephones and there has been no change in results. Though I have noticed some minor crackling and noise on the line, but I don't know if it's worth flagging it up. I'm not sure if this is a sign of a bad filter, but I don't wish to disturb the DLM by messing with things as I've heard many stories about its destructive ways, especially during the training period.
I'm not sure how old the cabling is, but I'm sure both the cabling and socket are quite old.
Previously when on LLU (IFTN chipset at the exchange), the downstream attenuation was around 40.5-42 dB (quite variable for some reason), but speeds of 6800-7200 kbps were the normal at 6dB. There were instances where connecting at 7800 kbps (more or less) was possible, and once before more than 8800 kbps was possible, but slowly as the day progressed the connection dropped as the SNR tumbled and I've never seen such speed again.
I've linked an imaged of my bitloading graph here if someone would like to view it.
I think that's everything I need to ask.
Advice and answers would be highly appreciated.