i was able to get my router upgraded to the latest 2.11 last night so all set. I created a guest network and put the 2 samsung tablet on that network.
while I was playing around with another working DIR655 at home (I have two units, one is broken) I discovered that the reason I had problem was that my home PC have default gateway set up as 10.10.10.1, and after the firmware upgrade the router is on 192.168. Anyway, that Emergency Recovery Mode fixed my router.
Thanks a lot.