UPDATE V2.37 firmware (r37)
it seems has settle down the jitter having the modem (in modem mode) continues ON

i am also getting lower ping with my 2850n router
(before with same router,had 10-12ms mainly..now down to 7-9ms)
Firmware look ok for modem mode(time will show) but download speed is poor ...but is always like that most of the times with VM