As mentioned earlier about the modem needing two attempts to synch, I'd noticed something similar on my TalkTalk supplied DSL-2780, running the current 2.02t TT firmware.
In fact, on my DSL-2780, it actually reboots between the initial attempt and the second one - if you're quick you can get into the web interface, be looking at the line stats, then find yourself disconnected from the modem as it restarts! Once it's done that it's very stable, so I don't think it's a fault as such.
I wondered if this was more of a bug than intentional.
Ian