Mystery Broadband problems

[JVaughan]

About a month ago my broadband started dissconecting every night, just the once between midnight and 2 am then reconnecting at a lower speed until it was below my guaranteed speed of 41 mbps.

The 1st openreach engineer said the line was perfect no noise and checked the connection up the pole, that night it did the same and the speed droped even slower.

The 2nd openreach engineer said the same, the line was perfect, reset the speed up to 55 and then the fun began, perfect for 2 nights then the  3rd night 120 disconnections over 2 days this settled as the speed lowered and the original problem reoccured of dissconecting the once in the early hours and reconnecting at a slower speed.

I managed to get a replacement router from an er110 to an er115 then a 3rd visit from the openreach engineer said the line was fine and did a lift and shift down at the green box and reset the speed to 55, the same occured as before, 2 days perfect then the 3rd night about 80 disconnections over 2 days.

Sky then sent a Sky engineer who changed the faceplate in the house, everything was fine for 2 days then it started dissconecting again for 2 days.

The 3rd openreach engineer returned with a tech expert, and found my line was saying interference, so they put me a new seperate line in from the house to the pole and the pole to the main pole on the main road, then reset it again to 55.

Everything was fine for 1 day then it has gone to the original problem of dissconecting once between midnight and 2am then reconnecting slower, it stayed connected Sunday night, and since then has stayed at 44 mbps when reconnecting, then last night between midnight and 2 am the router rebooted itself but still stayed at 44 mbps.

Any ideas anyone?

[Chrisee · Accepted solution]

@JVaughan the nightly disconnections sound like the automatic Digital Line Management system intervening as the number of data errors or disconnections exceed the programmed levels. A line can test as normal then have a burst of noise causing the issue. That the DLM reset did not work supports that conclusion. 

This scenario is not common but has been seen on a number of lines and has of course got an acronym REIN - repetitive electrical impulse noise - which has not surprisingly a companion SHINE - single high impulse noise event. These are explained here  with suggested causes so check thst nothing could be causing this in your home

Assuming the cause is external Openreach used to have specialist teams of engineers who got called in when the normal trouble shooting has not sorted the issue. Unfortunately now Openreach are moving over to fibre it is difficult to get them to take action unless a number of lines are affected so check with your neighbours. Sadly where Openreach wont take action Sky offer to release customers from their contracts which is pretty useless if you have no access to another network.

[JVaughan]

Thanks for the reply, just worked out why the router rebooted itself last night, it was updating the firmware.