Mine has gone bonkers and so has my Speedtouch 516v6, lol, it can't hold sync for more than a few minutes now, I get the feeling BCM6338 chipset doesn't work very well with a Ti DSLAM, hooked up the Westell Proline 6100 (Ti AR7) and it doesn't drop the line but SNR is all over the place.
Bit of a difference in power levels between the two routers as well:
ST516 DS: 19.5dBm US: 12.0dBm
6100: DS 16.9dBm US: 11.0dBm
Obviously the Proline can command the DSLAM to cutback power, pity that doesn't work on the Speedtouch.