Have I made a massive fail?! (pics)

About a 5 months ago I started getting random disconnections on my plusnet dslmax. It wasn't until plusnet phoned me to say they'd noticed an unusually high number of disconnects that I started trying to diagnose the problem.

After changing filters/router/cable plugging into test socket I found that the disconnections were happening whenever the phone rang. I pretty much gave up, but today I decided to have another look.
Firstly, my line stats as normal:
Router stats before.
Plusnet told me that my connection had been stable and fast (I live less than 500m from the exchange).

The flat I live in is a converted office, it has phone points everywhere. I noticed, upon taking the covers off these boxes, that the BT wire ran in, spurred off to the main phone point then also off to this massive white box. No other phone points are being used.
Cable entry point (photo)
Big white box of doom

So basically I cut the wire running into the Big White Box of Doom and now my stats say: THIS. Basically it dropped my attenuation from 23dB to 18dB, but my sync rate seems to have dropped?
AND the phone just rang and it didn't drop my connection. Was it a fluke? Did i do the right thing? And what the **** does the Big White Box of Doom do? (Apart from drop my connections apparently).
Thanks for any help!

The old box was probably a PBX (mini phone exchange for a business) and can cause oddities.

The drop in sync was not massive to be honest, so might just be the usual random variation. Though why at ~20dB you are not syncing higher is odd. Should be higher even with interleave mode set - the high target noise margin of 15dB won't help.

Time to sit back and see if line becomes more stable, and the automatic systems may lower the target margin on their own in two weeks.

Are you using a 3rd party program to generate the stats, or does that come with a specific model/make of router?

It's nice stuff. Far better than telnet.

Is this what you're looking for?

Kitz > link

You can disregard the sync change as lines normally fluctuate 100-200kbps at any given second of resync.

I think plusnet said they raised the target margin to help stability? Not sure. I'm currently being moved to adsl2+ (exchange has just been upgraded) hence why I took another look at the wiring, so obviously I'll go through another while of line training/setting, so hopefully it should settle down.
If the line settles right down on adsl2+ is it worth asking for interleaving to be turned off? I do use xbox live, although the lag hasn't been too bad.

Thanks for that, but it looks like my router isn't compatible.

Er, "The elephant in the room" is all that extra comms junk.
You say your flat is a converted office ? There doesn't appear to be much converted with all that gear left behind.
Your attenuation should attain a doubling ( or more ) of your existing speed when you've moved to ADSL2+, but if I was in your situation I'd want to know why all that stuff was left behind and what my position was in removing it all.
If should be a lot easier to fix faults/optimize your connection with it all removed.
I've seen flat conversions with some rats nests of wiring before but never a PBX left in situ !

In reply to a post by camieabz:

Thanks for that, but it looks like my router isn't compatible.

DMT tool versions 7/8 are for broadcom based routers. What router do you have ?

Solwise SAR 715

I tried the version that is recommended for the Solwise SAR 110/130, but no luck.