radius problem

Good Morning,
we have found some problems on radius, using RADIUS MANAGER, we think because of some declared clients’ account.
This is what happens: an account standard connected to radius has half bandwidth than declared for his profile. Instead an unlimited Account has the full bandwidth available on the BS.

In Detail, our client account was set up to 8Mb download and 1Mb upload with a resulting max download of 6Mb and 0.8 Mb upload.
Setting No-Limit option, our client gets 21Mb download and 26Mb upload.

After some attempts, changing account configuration and profile, either or enabling or disabling burst and changing priorities, we cannot solve the problem.

Note well: download bandwidth is always getting worse, instead upload is most of the times correct or near to be.
All our client side speed test have been made using www.speedtest.net.
Our question is: is that possible there is a wrong configuration on the pppoe servers? We use CCR or 1100AHx2

thank you