Power failure knocks 10mb/s off the line speed.

I really had no choice but to knock the power off to the modem yesterday. On reconnecting, thought I'd try a speedtest, 10Mbps loss. Ok, it's gone back up by another 3Mbps overnight but I'd have thought OR systems would be a bit more intelligent. After all, having been up for well over 3 months at one rate (lightning strikes caused the last failure), should one single cut immediately bring down the speed? In fact, thinking about it why does it get involved with playing with the line speeds on a stable line anyway. Haven't they ever heard of if it ain't broke, don't try fixing it.

Why did you have to turn off the modem? It could be relevant.

Probably not the BT systems but your modem deciding on the sync rate that can be achieved on connection.

As modems don't reconnect at higher speeds of their own accord then if the modem has not resynced overnight then the increase might be due to IP profile catch-up game at PlusNet.

The key is what are the actual connection speeds and stats from the modem, plus the Openreach DLM looks at error rates too.

While I might be an electrician, working live on 230volts isn't really recommended. I was swapping out some 13amp sockets for ones with USB sockets built in. So off went the MCB for about 30 mins or so. Wasn't a case of on and off as I changed each one but a simple off, then back on after finishing the whole lot.

One thing I noticed today was that on Plusnet, my line speed has also dropped from 78Mbps down to 67.4Mbps. I do wonder whether it's worth my while having words or wait until it goes back up.

Ummmm.

The immediate thought has to be what those inbuilt USB mains sockets are all about. I don't think you can assume they aren't the cause. What are they for, and is something now plugged into a couple?

Can you see the error stats on the Draytek?

What RobertoS is hinting at is that the switched mode PSU producing the USB might be a noise source and could be interfering with the VDSL2 signal.

One step to mitigating this if the sockets are to remain is changing RJ11 lead from a flat to twisted pair wire and at £2.99 its a cheap change to make https://www.amazon.co.uk/gp/product/B008IKVAP8/ref=a...

Agree with both answers so-far. One of the biggest impacts to VDSL2+ signals is noisy PSUs, which is why Christmas tree lights etc can often have such a big impact on broadband speeds.

It is very likely the PSU is generating electrical noise which is being picked up by the telephone wiring in your home, and more likely the RJ11 cable to the router, which is probably close to one of the USB power sockets.

10Mbps does not just fall off with a power failure. It has to be something changed and introduced more noise.

In reply to a post by RobertoS:

The immediate thought has to be what those inbuilt USB mains sockets are all about. I don't think you can assume they aren't the cause. What are they for, and is something now plugged into a couple?

Those USB sockets are used for charging only. Something like these USB sockets The wiring that they were connected to was a spur off the ring at the back of the house and the modem sockets are at the front. And no, nothing is yet plugged into them.

Edited by 69bertie (Thu 28-Jul-16 19:18:45)

In reply to a post by 69bertie:

In reply to a post by RobertoS:

The immediate thought has to be what those inbuilt USB mains sockets are all about. I don't think you can assume they aren't the cause. What are they for, and is something now plugged into a couple?

Those USB sockets are used for charging only. Something like these USB sockets The wiring that they were connected to was a spur off the ring at the back of the house and the modem sockets are at the front. And no, nothing is yet plugged into them.

Even so, they're switch mode power supplies with mains attached. These supplies can be less stable (and therefore more noisy) with no load on them. It may not be the model you have, but see https://www.youtube.com/watch?v=zoZ1_aEDPos , especially the section from 3:37 to 4:49.