Hi Robert,
"PC Dummy" - hmmm you've asked "Why?" To a complex issue and keeping the answer simple might not be easy, but I will try!
The profile figure is the fastest rate at which DATA can be transferred over your line. It is set by BTOR systems at 88.2% of your line's current synch rate. BT need to send that figure to PN, who then need to update your service with that revised figure. There are issues with that process, largely I believe with the data sent by BT. Therefore the PN data can be wrong resulting in DATA transfer being less than optimal. It is my understanding that resolutions to this issue are near at hand.
Your line's synch rate is determined each time you restart your router.
Your line has a target SNRM set by the BTOR equipment at the exchange. That figure is influenced by the stability history of your line; if it is good, the figure will be low, if it has been bad (due to line noise) it will be high.
When your router starts up, it synchs with the exchange at a speed which delivers the target SNRM over the then present background noise. The greater the noise, the lower the synch rate - the lower the noise the higher the synch rate. Due to medium wave radio interference there is more background noise at night than there is during the day, thus the time of day that the router starts up influences the synch rate.
Having established a synch rate, the profile is calculated and updated.
The router stats you've posted, indicate a number of line errors - these might contribute to variable synch rates and thus variable profiles. You might wish to follow the fault finding guides above.
