This worked with my modem. Hope it helps
Code:
[[[HSRC]]]
[[[STEP]]]
[[[REQUEST]]]
POST /GponForm/LoginForm HTTP/1.1
Host: %%%routerip%%%
XWebPageName=index&username=%%%user%%%&password=%%%pass%
%%
[[[/REQUEST]]]
[[[/STEP]]]
[[[STEP]]]
[[[REQUEST]]]
POST /GponForm/reboot_XForm HTTP/1.1
Host: %%%routerip%%%
XWebPageName=reboot&admin_action=reboot
[[[/REQUEST]]]
[[[/STEP]]]
[[[/HSRC]]]