ADSL 2+ problems

A friend is complaining of slow broadband speeds. Okay it's ADSL 2+, but we've seen speeds of maybe 15 in the past. He says he's getting maybe 3 Mbps on average at the moment.
Have just been looking in his modem/router. The attenuation reports 180 downstream.
Here's links to the statistics from the router :
https://ibb.co/eygfSA
https://ibb.co/frqULV
https://ibb.co/kmSb0V

So, downstream rate is 6656 but the attainable rate is 13584 (Kbps).
Downstream attenuation says it's 180, and SNR margin 146.
Is that just an unusual way of expressing attenuation and SNR margin, or do we have a serious problem here ?
I've run Fault Diagnostics tests on the line, KBD tool Non-intrusive and intrusive. Nothing of interest there - result "No issues have been identified in the BTW network. KBD test indicates no BTW network fault. Please perform all CP and End User checks. BTW Performance/Speed test has not been run."

My next step will be a visit to check things like internal wiring, dongles, etc.
But does anyone with experience have any recommendations ?

Oh, and at the ISP end, it's reporting multiple disconnections most days.

The easy bit is the high readings.

If you look at the descriptions they say 0.1dB. In other words they aren't printing the decimal points. So SNRM is 14.6 down, 5.9 up. Attenuation is down 18.0, up 8.4.

The more difficult bit is finding out what is wrong. The high down margin is causing the low sync, and the high down margin is a result of DLM trying to stop the frequent disconnections.

Normally the first thing to do is a re-sync to see if a one-off disconnection that re-sync'ed for instance during a thunderstorm, but given the ISP is seeing multiple disconnections it isn't that. So don't do it. In this situation the more re-sync's done his end the worse he makes it.

A guess. Plusnet?

Is he near to you so it's easy to pop round, or quite a way away and not simple for whatever reasons?

Thanks Robertos.
Firstly the easy bit - no not Plusnet, Entanet
He's not too far, about 15 miles. I'll probably not go until next week now as I've already got commitments for tomorrow evening, Friday daytime, all day Saturday. Then my better half is away with the girls Sunday & Monday so I'm not going to waste that free time

That router has been installed for quite a while. I'll maybe organise a replacement, just in case.
I'll feed back once I've been out and visited, and checked cables and stuff.
Thanks again.

Check the line for noise/dial tone too ... an easy test often overlooked.

Thanks Zarjaz
Quiet line test gives total silence.

You should be syncing at about 21 Meg instead of the 6656 K that you are. The reason you are not is that the DLM system has put you on a banded profile in response to past errors on your line, at the top of the 7th lowest of these ADSL Banded Profiles. You need to give the DLM time to relent & remove any banding. Leave it alone for at least 7 days & don't reset or resync the router. If it's still banded you should then call your ISP to get the DLM reset in order to remove any banding. However should significant errors persist the DLM will reapply banding.

OK, that�s a good start then. It�ll have await your visit then.

ADSL is an outdated technology.

What a pointless post to make ? Doesn�t help the original poster at all does it ?

Without getting into anything more right now, can anyone confirm that this is a very old BT "master" socket ?
Link : https://ibb.co/nM5VVV

I need to go out for a few hours, so don't be offended if I don't respond right away to any replies