I need to create a script that automatically configure a vigor 2820 through a telnet session; anyway I cannot find a way to change the IKE phase 2 proposal, at the moment I'm able to change the phase 1 using the following command:
vpn l2lset 1 main 4 (for 3DES-SHA1-G1)

Hi,
if somebody else is looking for a solution, this is what the Draytek support told me:

I am sorry.Router doesn't have the facility to change or configure phase 2 proposal via telnet.