Internet speed lower than Speedtest.net results during actual download

There are many factors that impact the speed of a specific download.

Among these are distance to the server, number of hops between you and the server, the capabilities of the server, the load on the server, the number of devices on your connection, other bandwidth needs of your own computer, and a myriad of other things.

Speedtests show you a baseline optimized speed and are generally built to indicate the maximum possible connection speed.

Speedtests are NOT a guarantee or even an indicator of the speeds you should expect to receive in real downloads.

Further to the answer above there is also a bandwidth overhead associated with A/VDSL somewhere in the ballpark of 10% as well as another figure for the generic IP packet overhead.

A study Encapsulation Overhead(s) in ADSL Access Networks puts the overhead at anywhere from 10 to 20% of your line speed. In the conclusion of that study they state:

Generally speaking the “line efficiency” of a protocol stack/encapsulation is roughly 80% given the Internet packet distribution.

Which means that your "effective" line speed is actually somewhere below (11264kbps - 1126 = 10138kbps) which is approximately 10Mbps.

The fact that you are getting pretty close to 10Mbps suggests that you are much better off at closer to 10% overhead rather than the 20% encapsulation overhead.