Greetings. I'm new here (and new to BT) so please bear with me!
I recently decided to change from Demon to BT on the basis that BT is now offering FTTC in our area. It's a two-stage process; we moved from Demon ADSL to BT ADSL last week and following some delays in the order process we expect to move to FTTC in a week or two. BT has supplied a Business Hub 3 router to replace the elderly Thomson 580 and this is connected via the test socket. There's nothing else connected to the line at all.
Generally speaking this Demon/Thomson ADSL setup has provided very stable (if slow) connections at about 25-2600kbit/s and worked well for a number of years.
Having moved to BT and changed the router, I thought at first that the line must be heavily contended. Internet access slowed down to the point of unusability every few hours and e-mail access was so slow that the servers timed out! Looking at the router stats using RouterStats Hub suggests something a little strange and I'd greatly value some insight into what's happening.
The downstream noise margin is very consistent at 19dB. Following a router reboot, the upstream noise margin starts out at about 7dB and degrades gradually over a period of about 12hr to about 3dB. The connection speed remains constant at about 2625kbit/s during this period. By the time the noise margin has reduced, pages are extremely slow to load and e-mail is frequently subject to server timeouts. Rebooting the router immediately restores the indicated upstream noise margin to about 7dB and normal internet and e-mail operation is restored. The line does not seem particularly prone to FEC or CRC errors and the upstream and downstream loss is consistent.
I'm sure that rebooting the router every twelve hours or so isn't ideal from the DLM point of view but if I don't do so our internet and e-mail become so slow as to be unusable. The odd thing is that the indicated connection speed never changes. It's been sitting at 2625kbit/s since I re-booted at about 0740 this morning but the noise margin is currently 3.8dB, having started at 7.2dB this morning.
Can any kind soul please explain what's happening?
