Any way to change FOV Smoothly Through server scripts?

Ive tried some ways changing FOV In server scripts

local cam = game.Workspace.Camera

cam.FieldOfView = 100
wait(4)
cam.FieldOfView = 70

local cam = game.Workspace.Camera

for i = 1, 10 do
	cam.FieldOfView + 2
	wait()
end

for i = 1, 10 do
	cam.FieldOfView - 2
	wait()
end

None of these work, (i want these to show for all players) first script is supposed to be just setting the fov, second script i wanted to do kind of a tween and inbetweens make it go up and back down but none of these work?

Use tweenservice to smoothly change the FOV