Interleaving: How can I tell?

[#1]

Is there a way I can tell from my router stats whether interleaving has been enabled or not?
Some background:
Towards the end of last week I had a spate of disconnections, which started with occasional loss of internet connectivity (and difficulty reconnecting) while maintaining sync. It progressed by Friday lunchtime to losing sync every few minutes. By that point I'd tried a different router (my old Thomson 585v8) and connecting to the master socket, and it wasn't helping. I reported a fault via the website, and within an hour was notified that tests had started -- at which point the line miraculously settled down, stayed in sync for about nine hours straight, and only dropped occasionally over the weekend. At one of the drops that did happen, my upstream speed reverted to 445, which is a little sad, but the downstream speed stayed at 14333, where it's been ever since an earlier bout of trouble a few months ago. (That cleared up on its own before I could bring myself to report it, but left me with an SSN of 9, when previously I'd had 3-ish and sync speeds around 18000.)
On Tuesday I received an automated-looking email with no reference to the fault ticket, letting me know that "We have asked our wholesale broadband suppliers to turn interleaving on on your phone line to try and fix your current broadband problem." There was no indication of how I would be able to tell when this had happened.
Yesterday morning (Wednesday)  I got fed up of having a power cable running across my kitchen doorway and resumed using my shiny new Asus DSL-N55U router on the bedroom extension as usual. Since then the line has dropped exactly once -- apparently coinciding with the end of the testing, as I received an update on my support ticket ten minutes later, saying essentially that they couldn't find a problem.
Right now my stats look like this after nearly 20 hours of uptime:
Modulation : ADSL2+
Annex Mode : Annex A/L
Line State : up
Lan Tx : 1703348
Lan Rx : 1122814
ADSL Tx : 680774
ADSL Rx : 1093626
CRC Down : 0
CRC Up : 225
FEC Down : 0
FEC Up : 11498
HEC Down : 9582
HEC Up : 0
SNR Up : 25.4
SNR Down : 8.5
Line Attenuation Up : 11.9
Line Attenuation Down : 20.0
Data Rate Up : 446
Data Rate Down : 14333
So my question is: is interleaving on or not? And if it isn't, and the line continues to behave itself, is it needed? My suspicion is that something got messed up at the exchange and the process of initiating testing somehow cleared it.

[#2]

Any value for FEC will show that interleaving is active on your line. In your case interleaving appears to be on for the upstream but off for the downstream.
There are instances when routers sometimes report a value for FEC but is extremely high, these are usually considered as a bug and not actual figures (they also tend not to change in number, so obivous to tell as incorrect).

[#3]

Quote from: RPMozley

Any value for FEC will show that interleaving is active on your line.

Thanks, that's helpful information!

[#4]

I suspect the CRC and FEC up / down numbers are reported the wrong way around by your asus, it's more likely it should have been FEC Down : 11498 and CRC Down : 225.

[#5]

Well, it is the upstream sync speed that's dropped ...
(1200 up was nice while it lasted. :()

[#6]

The upstream speed drop is because your upstream speed has been capped. Someone from Plusnet will have to place an order for it to be uncapped again.

[#7]

That would be nice if it didn't upset anything else, but is uncapped upload compatible with interleaving?

[#8]

Morning saguaro,
I've placed the order to uncap the upstream which should complete in the next 24-48 hours. It wont change anything else on the line including interleaving.
Dan

[#9]

Thanks, Dan! That's good to hear.

[#10]

It seems to be a knee-jerk reaction by Faults agents to cap the upstream when dealing with this type of fault, so it's probably written in a procedure document somewhere.
They should be made aware that capping the upstream should only be done in extreme cases where it can help, and not in every case - a last resort rather than a first.