Just bought a new Draytek 2820n, the router keeps on droping Tisacli ADSL Line, configured as WAN 1, every few minutes.

I have a BT broadband running on WAN2 (Ethernet) ok.

I have tried firmware 3.3.3_232201 (current), 3.3.4, 3.3.4.1 and 3.3.5 and have same problem on all firmware.

My old belkin N= worked fine. but I upgraded to get 2 ADSL lines linked.

Has anyone else had similar asl line drop problems with Draytek 2820n. and can suggest fix