G.fast sync speeds have halved

[neil_cm17]

I got G.fast last year and at first all was well and I was getting the full 330Mbps down, as the cabinet is right outside my flat, and the line length is under 300m.  I'm now getting a sync speed of under  150Mbs.  I've had two separate engineer visits, that couldn't find anything physically wrong with the line and both times the line was reset which seems to fix the problem for about a week before the speed starts dropping again.  The connection has also dropped a lot recently.

It also looks there is a problem with the BT speed checker as when I run a speed test I get an error message saying "Your Stay Fast Guarantee could not be found".

I've attached my router stats.

[pippincp]

Any noise on your line? 17070 option 2, best with corded phone.

[neil_cm17]

I couldn't hear anything out of the ordinary there is slight bit of low level noise in the background, but no cracks, pops etc.

 My download sync speed has now dropped to 125.95 Mbps.

[neil_cm17]

Openreach have reset the line so it's now syncing back at 330Mbs but as soon as I do a speedtest the speed immediately drops down to 220Mbs.

[neil_cm17 · Accepted solution]

Turns out the problem was down to the fact that I had a pair home plugs running and it looks like they generate interference on the same frequencies that G.fast uses.  After disconnecting them the connection has returned to normal.