Sorry, bit late on this as I notice you have found a solution, but I thought it may be worth posting in case anyone else is having difficulty setting time.
Im not using bridge mode, but these are my settings from within the GUI, which work for me:-
I use the IP addresses for NTP servers at mcc.ac.uk & london.telehouse.
130.88.203.12
194.164.127.6
That way if DNS isnt working - or if the router attempts to get time before DNS is allocated - then it should still be able to access a time server.
iirc by default it attempts to get time from various listed ntp servers - Im quite certain that my default was set to tummy.com. I found that when looking at my logs there used to be long lists of synchronising with tummy and sunsynchronising with tummy.com at various times which appeared to have nothing to do with me rebooting or resyncing the modem.
Since putting in the IP addresses I only get the synchronised messages after I've reconnected and Ive never had to set anything within the CLI for anything time related.