I'm using a Netgear DG834GT loaded with
DGTeam firmware, can tweak the SNR value which helps on the longish line to achieve a higher sync speed and the connection stays up for days on end providing the IP profile is no greater than 3500kbps.
These are the current line stats:-
Channel: INTR, Upstream rate = 448 Kbps, Downstream rate = 4000 Kbps
Link Power State: L0
Mode: G.DMT
Channel: Interleave
Trellis: ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 7.4 17.0
Attn(dB): 61.5 30.0
Pwr(dBm): 19.3 12.0
Max(Kbps): 4352 892
Rate (Kbps): 4000 448
If the sync rate gets the IP profile up to 4000kbps or even greater then the connection can get unstable if it's used for more than just basic browsing and e-mails.
( I've got another one spare, it too came via eBay

)