Additional info,

The web interface doesnt allow you to access the router as soon as the problems start. The lights all show healthy status.....

I've been having exactly the same problem over the previous two days, at two different houses (both on Naked ADSL with the TD-VG3631 modem), after months of trouble free internet access ?!?!!
Really starting to annoy me - having to restart the modem every 10-15 minutes. No internet access, DHCP stops giving IP addresses, can ping other network devices, but cannot access internet, or web interface for modem.

Region : Australia

Model : TD-VG3631

Hardware Version : V1

Firmware Version : 0.6.0 1.0 v0001.0 Build 130413 Rel.52459n

ISP : Internode

Do as the followings:
Go to the management Interface,
Choose "USB Settings---Print Server ---Stop",and then it will be OK

Thank you, thank you, thank you! This seems to have worked ... fingers crossed it'll stay working.
Very strange how two modems at different locations develop the same issue at exactly the same time though :/