Those stats confirm that you're on a very short line, and if the connection wasn't capped at all you could get a downstream connection speed of well over 20 Mbps (probably the ADSL2+ maximum, 24 Mbps).
The hole around tone 310 is of little or no consequence, and it certainly isn't affecting your speed at the moment. These gaps are often caused by medium wave radio stations, but there are many other possible causes. If there isn't any likely local source of interference at this frequency, then it's probably not worth trying to locate it.