At 1st my PN connecton was at 73 Mbpsthen after 3 days it started to drop to an also acceptable 66mbps. For the last few days it has dropped again down to 54Mbps. Is there a problem, I understand that the inital speed may vary but this is quite a drop, what can cause this sort of thing? My UL speed has also dropped from an inital 16.6 to 13.87.....