While using the vi editor, you wish to move ahead one page. You should press the control key and:

Ctrl+A is not a standard vi page-navigation command and has no defined scrolling behavior in vi.

Ctrl+D scrolls forward by only half a page, not a full page.

Ctrl+F is the vi keybinding for 'forward one full page,' scrolling the viewport down by one screen. This is part of vi's standard navigation set, where the F mnemonic stands for Forward. Its counterpart, Ctrl+B, scrolls backward one full page.

Ctrl+U scrolls upward (backward) by half a page, which is the opposite direction and half the distance.