Powerline adapters and VDSL interference

I am about 780m from my cab., and have an FTTC connection (no FTTP here). For some while the connection had been unreliable, dropping out 2-3 times a day typically. The router event log often contained messages suggesting that a drop might have been caused by interference to the VDSL signal from a powerline adapter.

I have a security cam under the roof driven by an old Mk 1 RPi, which streams video over ethernet to any PC on my network. The RPi doesn't support wifi natively, and while I have a USB wifi adapter for it, that isn't up to streaming video. So I had been using a pair of powerline adapters to network the RPi.

Because of the dropouts, and the fact that the powerline connection wasn't that good anyway, over Christmas I bit the bullet, lifted a few floorboards, and ran a cat6 cable direct from the RPi to my switch. The powerlines have been disconnected, and it's been running like that for a month now. Not only is the video feed much better, but the VDSL dropout rate has improved, maybe only once every 2-3 days now. But when the internet does drop out, the router log still suggests powerline interference as a possible cause, even though mine are disconnected.

Some questions for the techy gurus out there:

- would the router (Fritz!Box 3490 from Zen) have evidence of interference, or is it just some routine message it sometimes puts out anyway on loss of sync?
- how likely is it that the powerlines were causing interference?
- or is the improvement just coincidence?
- how far do powerline signals travel over the mains? Could one of my neighbours' bits of kit occasionally be interfering?
- I'm syncing at around 30Mb/s now. At my distance from the cab., is that and my current dropout rate now reasonable?

In reply to a post by Thaumaturge:

- how likely is it that the powerlines were causing interference?

Very likely.

I used to run DSLStats with my FTTC and there was a massive jump in FEC and an increase in ES (errors) whenever data was being transferred over my powerline adapters.

I've read literally hundreds of posts over the years where powerlines were identified as the cause of issues with their FTTC circuit.
Some had a slight increase in errors while others suffered huge bursts of errors or regular disconnections.

The issue is considerably worse when the circuit with the xDSL signal runs parallel to your homes electrical wiring.
I had a double power socket right next to my Openreach master socket.
I had a friend who's an electrician move the double socket (along with the electrical wiring feeding the socket) a few metres away from the Openreach master socket.
After that using powerlines stopped causing any issues.

I always suggest avoiding powerline adapters/homeplugs while using a VDSL2 (FTTC) service.
Some people are fortunate and have no issues with them at all.

@Thaumaturge I have had interference problems with powerline networking kit in the past so no longer use them. They are prone to generating electrical noise and there are reports of not only neighbours powerline equipment causing interference but also allowing connection to their powerline network because security passwords have not been set up which causes great confusion when you expect to be connected via TalkTalk but are on Plusnet instead.

In reply to a post by j0hn83:

I always suggest avoiding powerline adapters/homeplugs while using a VDSL2 (FTTC) service.
Some people are fortunate and have no issues with them at all.

I always suggest avoiding powerline adapters full stop

Thanks for replies. I will provisionally assume that the powerlines were (one of) the problems, possibly the main one.

Should have put in the cable before, but it's not a simple run, between floors and under the floorboards, and I'm not as young and agile as I was once.

Bit disappointing that in all the conversations I've had with Zen tech support about the line drops, they never once suggested this as a possible issue. DLM kept capping the line, and I was regularly phoning them to get the cap taken off. We had a plan to go through a test procedure (connect direct to the master socket, eliminate phone extension wiring, turn off bits of electrical kit one by one etc) but with hindsight I don't think this would have caught it. I probably wouldn't have thought of the powerlines, they were out of sight, out of mind.