Broardband Profile

I am rather new at this and do not fully understand what is technically happening so I would be very grateful if anyone could enlighten me.

My ISP (UW Club) Telecom Plus changed my profile from 15dB to 12dB as the connection kept failing. What does this mean? How can they do this and can I alter the profile myself? What happens when the profile is changed? Does altering the profile change the speed of connection?

I checked the speeds with your meter today and this afternoon I got 5.78Mbs but this evening I am only getting 3.61 Mbs. Why should this be and is there anything that I can do about it?