Symptons of a long line or something else?

[#1]

My connection is showing massive error increase which occur overnight with frequent loss of PPP link. This morning the internet light was showing red on the router. I've always found the best thing to do is to reboot the router and during the the day the errors are much less and the PPP link is stable.
I'm a light user of the net and the 2.5 profile is ok for my use so I'm thinking of routinely switching off the router daily  to avoid these overnight error problems. Any thoughts on this or can this problem be fixed considering my line is long, 5.8 km according the the BT database.
Here are the line stats etc with the last showing the rebooted router stats.

[#2]

I have always used a rule of thumb of 15db of attenuation per km of line in which case your line length is 54/15 = 3.6km.
Noise levels tend to get worse at night because pick-up of radio waves in the wiring adds to your broadband noise and radio waves travel further at night.  Switching off your router at night may help at the moment but what will you do in the winter when it's dark all evening?  If I were you I would get hold of RoutersStats http://www.vwlowen.co.uk/internet/files.htm and use it to monitor the router to get a clearer idea of what is going on.

[#3]

I did check with router stats once overnight and only found a gradual reduction in the snr from 8 to 5, nothing more. As far as the line length goes even as the crow flies I am at least 5 km from the exchange, I  know the 54db attn does not match a 5.8 km line length by the usual calculations but that is what it is.

[#4]

Quote from: mikehvy

... a gradual reduction in the snr from 8 to 5, nothing more.

A 3dB change is quite a lot, although I have seen worse.  But did you monitor this before your night time instability arose? 

[#5]

I did the routerstat check some months ago. My line has always behaved like this and the BT routers were unable to regain the PPP link and were less stable than the Plusnet TG582n router. I used to only switch the BT routers on during daytime as I could end up with a 1.5mb profile. I will try another routerstats overnight just for curiosity.