To add further to Gary's comments .............
I realise you're a gamer, but having your latency (Interleaving depth, Run-mode, Connection-mode ...... all mean the same) set to 'FAST' on a line of your length, is just asking for trouble. As Gary has mooted, your 'errors' will increment causing massive instability. I would insist that you are reverted back to 'INTERLEAVED'. Yes, slightly increased 'ping' but give me that over 'time-outs' any day.
Regarding the attenuation difference, that could even be your new router that's got a greater resistance than the previous one ?? For clarity, could you plug your old router back in and get the stats, then plug the new one in straight away and do the same 
If it does prove to be a line fault caused an attenuation shift, you are in the fortunate position of being able to request a 'RADE1' task. These are only built if the attenuation has altered by more than 6dB since initial 'Base-line loss' data was stored in the DLM. In other words, if with the same router plugged in the attenuation has increased from what it was when you were first activated, (and you haven't added any extentions etc etc ), then there is obviously a fault somewhere, because your house hasn't moved nor has the Exchange. 
You need to be in the test socket with the same router, and I would listen on 17070 option 2, (Quiet line test), to put the circuit under full load to see if noise is heard. Humming noises are usually what we would call an 'Earth fault'. Crackling noises are usually 'High Resistance faults'. Both can play silly buggars with your attenuation. The key is to double-check everything so the blame cannot be laid at your door. 
The line was working fine after I had 'Fast' enabled for a couple of month (I think) I shall request it to be changed back to be sure.
Regarding attenuation: My ISP informed me I had a 53 last summer. The first line stats I posted from july/11 were 56.
These stats are from 3/2/12 with my previous router (WAG54GS) shortly before I swapped to the 7800N.
# adslctl info --stats
adslctl: ADSL driver and PHY status
Status: Showtime Channel: FAST, Upstream rate = 448 Kbps, Downstream rate = 284
8 Kbps
Link Power State: L0
Mode: G.DMT
Channel: Fast
Trellis: ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 11.6 17.0
Attn(dB): 55.0 31.5
Pwr(dBm): 18.2 12.3
Max(Kbps): 2880 900
Rate (Kbps): 2848 448
G.dmt framing
K: 90(0) 15
R: 0 0
S: 1 1
D: 1 1
ADSL2 framing
MSGc: 1 1
B: 90 15
M: 1 1
T: 1 1
R: 0 0
S: 1.0000 1.0000
L: 728 128
D: 1 1
Counters
SF: 14799290 14799288
SFErr: 2569 0
RS: 0 0
RSCorr: 0 0
RSUnCorr: 0 0
HEC: 951 0
OCD: 0 0
LCD: 0 0
Total Cells: 1689913322 0
Data Cells: 22220724 0
Drop Cells: 0
Bit Errors: 0 0
ES: 1698 0
SES: 5 0
UAS: 9 0
Total time = 1 days 21 hours 48 min 27 sec
SF = 14799290
CRC = 2569
LOS = 0
LOF = 0
ES = 1698
Latest 1 day time = 21 hours 48 min 27 sec
SF = 4618004
CRC = 1267
LOS = 0
LOF = 0
ES = 637
Latest 15 minutes time = 3 min 27 sec
SF = 12174
CRC = 6
LOS = 0
LOF = 0
ES = 6
Previous 15 minutes time = 15 min 0 sec
SF = 52930
CRC = 10
LOS = 0
LOF = 0
ES = 10
Previous 1 day time = 24 hours 0 sec
SF = 5082263
CRC = 639
LOS = 0
LOF = 0
ES = 471
15 minutes interval [-30 min to -15 min] time = 15 min 0 sec
SF = 52931
CRC = 0
LOS = 0
LOF = 0
ES = 0
15 minutes interval [-45 min to -30 min] time = 15 min 0 sec
SF = 52989
CRC = 11
LOS = 0
LOF = 0
ES = 5
15 minutes interval [-60 min to -45 min] time = 15 min 0 sec
SF = 52930
CRC = 126
LOS = 0
LOF = 0
ES = 41
#
#
I shall plug the WAG back in and capture some stats shortly.
regarding quiet test: Do you want me to plug the router and a wired phone through a filter or just use a splitter?
Which router (I'm getting confused!).
DL/UL a file while I listen for any noise, yes?
