Sync determines the IP Profile.
When the IP Profile changes the ISP should get an automatic notification to change their Current line speed
. They usually change it to a fraction below the IP Profile. The ISP change is usually a few hours later and should always be well under 24 hours later.
For whatever reasons, that notification or automatic update of the ISP one can fail. If that happens then the ISP one will stay incorrect until the next IP Profile change, which will only be when you have a re-sync.
Note that a downward IP Profile shift can also fail to update the ISP copy. In which case it is the IP Profile that determines the maximum throughput. It is always the lower of the two, as BT Wholesale limit it to the IP Profile.
The indispensable man or woman passes from the scene, and what happens next is more or less the same thing as was happening before.
My broadband basic info/help site - www.robertos.me.uk.
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Connection - AAISP Home::1 80/20. Sync 59997/15142kbps @ 600m. - BQM