I got 1mb connection last month. It was working smoothly as I was getting 128kb download and 65kb upload (modem CP showed 1024k upload and 4096k download) but the modem Huawei MT880 did not tolerate small electricity fluctuations and restarted many times a day. I lodged a complaint which was promptly attended. A techie came with a new modem but advised me to keep MX880 as it was best.
I was not satisfied with my upload speed so I asked him to see if it can be increased. He checked Modem's CP and said SNR was low. He changed Operation Mode from ADSL2+ to Automatic; modem rebooted and connected in G.DMT mode instead of ADSL2+ which increased upstream SNR. He said everything was Okay and he will get my line profiled which will be done in 2/3 days.
Now since yesterday I noticed decrease in my speed; checked CP and found modem connecting at 256K/1024K instead of 1024k/4096k. SNR and other readings are:
Now I get maximum speed of 30kb upload and 108kb download; loss of 20-25kb both ways. When I called the techie he told me modem speed is exactly 1mb and that is what I applied for. Line Profiling cannot be undone.
IMHO Line Profiling is something that should always be avoided.