How do isp increase bandwidth

As above, with cable & wirless adsl2+ asked the isp to increase my bandwidth as not getting what i have been promised but now looked at stats and all they have done is lowered the snr margin from 9db to 6 db but my upload speed has gone down from 1023mb to 0.4mb on router stat can they not increase download speed and also keep upload same....i think they are trying to cheat with me, just by lowering the snr margin with slight increase in download speed....old stat said 6.1 mb d/l 1mb u/l snr margin 9-10db but getting 5.4mb thru speed NOW 6.8mb d/l 0.4u/l 4-6db snr margin getting 5.6- 5.7mb thru speed....why cant they increase my actual bandwidth instead of tweaking the snr margin.

What are the current upstream and downstream attenuations?

Your 6.8Mbps downstream sync would be about right on an ADSL2+ 49dB attenuation with a 6dB SNRM...

Your bandwidth on ADSL is dependent on your distance from the exchange. Might be able to increase if you have FTTC available.

What they have done is a small tweak to use some "spare" SNR. However, the SNR may have been high to give a stable connection so you may have traded some stability for speed. It also sounds like they may have moved you from ADSL2+ to ADSL which is what has dropped the upstream (EDITED to correct error) speed lower.

You need to get them to move you back to ADSL2+ and you are not going to get anymore speed really unless you can change technology (or move your house closer to the exchange).

Can you post full stats (attenuation, speeds, SNR) straight from the router? Then we may be able to comment further.

Edited by ian72 (Sun 18-Aug-13 16:10:10)

In reply to a post by ian72:

It also sounds like they may have moved you from ADSL2+ to ADSL which is what has dropped the down speed lower.

Good point about the possible change from ADSL2+ to ADSL1, but as a consequence did you mean that the upstream sync speed is now lower?

Indeed I did.

Current figures
DSL Type: ITU-T G.992.5
Bandwidth (Up/Down) [kbps/kbps]: 509 / 6.998
Output Power (Up/Down) [dBm]: 12,4 / 18,0
Line Attenuation (Up/Down) [dB]: 24,2 / 42,0
SN Margin (Up/Down) [dB]: 24,3 / 4,3
through speed 5.2-5.5mb ish.

Before figures
DSL Type: ITU-T G.992.5
Bandwidth (Up/Down) [kbps/kbps]: 1.023 / 6.300
Output Power (Up/Down) [dBm]: 12,6 / 18,5
Line Attenuation (Up/Down) [dB]: 23,0 / 40,0
SN Margin (Up/Down) [dB]: 6,7 / 8,8
through speed around 5.4-5.7 ish.

I see the sn margin has changed and download not improved that much.

Edited by deleted (Sun 18-Aug-13 16:10:49)

The upstream speed is still there just for some reason the SNR has shot up - have you tried restarting the modem to see if it clears it. If not the ISP might be able to release whatever is holding the upstream back as there is SNR to spare.

Yes you are still on ADSL2+ but for some reason the upstream SNRM is now 24.3dB which has reduced the upstream sync to 509Kbps.

For example, a 42dB downstream attenuation on a 6dB SNRM with ADSL2+ should give a sync speed in the region of 7200Kbps. So your downstream sync is looking reasonably OK

no not restarted as i have been told not to touch router as they are still trying to resolve my problem had constant dropout after 4-5 hrs so they changed linecard its now stabalised but why instead of tweaking snr margin cant they up my download sync speed to 11mb then tweak snrm....previusly getting 7mb actual download speed with old isp been informed differnt technology WHY they both use adsl2+ i.e 992.5 so whats different....can anyone tell me from my stats if they are trying to cap me from the info.

What makes you think your line can do 11Mb/s? Has it done that speed before? It could just be as good as it is going to get.