My connection has been stable for several months now, connecting at 29,677 kbps adn give download speeds of around 21Mbps on both Thinkbroadband Down TBBx1 test and the Down HTTPx6 tests, with upload speed of 5.76Mbps.
In the last few days the connection speed remains unchanged, but the download speed on the Down TBBx1 test has dropped to around 8Mbps while the Down HTTPx6 speed remains at 21Mbps.
I have run the tests at several times of day or night all with around the same gap between the two tests
This looks like a congestion issue at the servers - please can you look to see if there is any known issue at the exchange / server end?