System Up Time 01:08:00
Port Status TxPkts RxPkts Collisions Tx B/s Rx B/s Up Time
WAN PPPoA 7624 9735 0 279 1873 01:07:18
LAN 10M/100M 268 0 0 15 0 01:07:52
WLAN 11M/54M 11236 9297 0 1967 361 01:07:43

ADSL Link Downstream Upstream
Connection Speed 4544 kbps 448 kbps
Line Attenuation 38.0 db 21.5 db
Noise Margin 11.6 db 20.0 db

Nothing obviously wrong there (apart from your sync being lower than expected, probably because your SNR margin has been raised).

Would be worthwhile to check error info.

See if http://192.168.0.1/setup.cgi?todo=debug enables debug mode (replace the 192.168.0.1 with your router's address).

If that works go to a command prompt and launch telnet.

e.g.

telnet 192.168.0.1

depending on your model/version number either

cat /proc/avalanche/avsar_modem_stats

or

adslctl info --stats

should report the error stats.

In reply to a post by captainmouse:

ADSL Link Downstream Upstream
Connection Speed 4544 kbps 448 kbps
Line Attenuation 38.0 db 21.5 db
Noise Margin 11.6 db 20.0 db

Are you still on Vivaciti Family 30 with a DG834G v4 router?

adslctl: ADSL driver and PHY status
Status: ShowtimeRetrain Reason: 0
Channel: INTR, Upstream rate = 448 Kbps, Downstream rate = 4544 Kbps
Link Power State: L0
Mode: G.DMT
Channel: Interleave
Trellis: ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 11.4 20.0
Attn(dB): 38.0 21.5
Pwr(dBm): 19.8 11.3
Max(Kbps): 5088 1080
Rate (Kbps): 4544 448
G.dmt framing
K: 143(0) 15
R: 16 8
S: 1 8
D: 32 4
ADSL2 framing
MSGc: 1 1
B: 143 15
M: 1 8
T: 1 1
R: 16 8
S: 1.1111 8.5000
L: 1152 128
D: 32 4
Counters
SF: 326092 326094
SFErr: 1 0
RS: 22174286 2770796
RSCorr: 914 0
RSUnCorr: 23 0

HEC: 1 0
OCD: 0 0
LCD: 0 0
Total Cells: 59410624 0
Data Cells: 176888 0
Drop Cells: 0
Bit Errors: 0 0

ES: 1 0
SES: 0 0
UAS: 22 0
AS: 5543

INP: 1.77 1.00
PER: 1.94 1.85
delay: 8.88 8.50
OR: 28.80 30.11

Bitswap: 0 0

Total time = 1 hours 32 min 57 sec
SF = 326092
CRC = 1
LOS = 0
LOF = 0
ES = 1
Latest 1 day time = 1 hours 32 min 57 sec
SF = 326092
CRC = 1
LOS = 0
LOF = 0
ES = 1
Latest 15 minutes time = 2 min 57 sec
SF = 10443
CRC = 0
LOS = 0
LOF = 0
ES = 0
Previous 15 minutes time = 15 min 0 sec
SF = 52923
CRC = 0
LOS = 0
LOF = 0
ES = 0
Previous 1 day time = 0 sec
SF = 0
CRC = 0
LOS = 0
LOF = 0
ES = 0
15 minutes interval [-30 min to -15 min] time = 15 min 0 sec
SF = 52923
CRC = 0
LOS = 0
LOF = 0
ES = 0
15 minutes interval [-45 min to -30 min] time = 15 min 0 sec
SF = 52982
CRC = 1
LOS = 0
LOF = 0
ES = 1
15 minutes interval [-60 min to -45 min] time = 15 min 0 sec
SF = 52923
CRC = 0
LOS = 0
LOF = 0
ES = 0
Showtime Drop Reason: 0
Last Retrain Reason: 0
#

In reply to a post by RobertoS:

Thanks.

No prob.

The Apple USB to ethernet adaptors are £19 on Amazon, silly money for what they are, but worth their weight in gold when it comes to trouble shooting one of the Airs. In practice I suspect the Apple adaptor will fit the Air but will be unusable on another machine. Can't see why one of the cheaper ones wouldn't fit an Air, but there may be custom firmware in the Apple adaptor.