why does Localscript not edit Server Workspace but Clientside Workspace?

I was making a game where a 3d box moves into an outline and you have to press a certain key to hit the 3d box. It works perfectly using the Play button in roblox studio, but when I use a server, everything just stops working correctly. On the server screen, nothing is moving; but on the client screen, things are moving but input is completely ignored, as if these were two different programs.

Problem I noticed that local scripts only edit Clientside Workspace, which is the workspace that appears for you, which I found odd because usually it does not do this. It works if I change it to a global script, but I still cannot access keyboard input without using a local script. I tried using boolvalues that the local script would set true and the global script would detect so that it would run the functions for them but, as stated earlier, the local script affects the Clientside Workspace not the Server Workspace, so the values appeared true on the client screen but appeared false on the server screen.

Question How do I make functions that affect the Server Workspace when pressing a key on the keyboard?

global script -- used to do global work for localscript

wait(0.5)
Instance.new("BoolValue", script.Parent.GuitarKeyScript).Name = "keyXpressed"
Instance.new("BoolValue", script.Parent.GuitarKeyScript).Name = "key0pressed"
Instance.new("BoolValue", script.Parent.GuitarKeyScript).Name = "key1pressed"
Instance.new("BoolValue", script.Parent.GuitarKeyScript).Name = "key2pressed"
Instance.new("BoolValue", script.Parent.GuitarKeyScript).Name = "key3pressed"
Instance.new("BoolValue", script.Parent.GuitarKeyScript).Name = "key4pressed"
Instance.new("BoolValue", script.Parent.GuitarKeyScript).Name = "key5pressed"
Instance.new("BoolValue", script.Parent.GuitarKeyScript).Name = "key1lifted"
Instance.new("BoolValue", script.Parent.GuitarKeyScript).Name = "key2lifted"
Instance.new("BoolValue", script.Parent.GuitarKeyScript).Name = "key3lifted"
Instance.new("BoolValue", script.Parent.GuitarKeyScript).Name = "key4lifted"
Instance.new("BoolValue", script.Parent.GuitarKeyScript).Name = "key5lifted"
print("valuesmade")
while true do
	if script.Parent.GuitarKeyScript.keyXpressed.Value == true then
		script.Parent.GuitarKeyScript.keyXpressed.Value = false
		if game.Workspace.Guitar.Overdrive.Value >= 50 then
			game.Workspace.Guitar.Overdrived.Value = true
		end
	end
end

local script -- used to detect key presses on keyboard

wait(1)
local mouse = game.Players:FindFirstChild(script.Parent.Name):GetMouse()
workspace.CurrentCamera.CameraType = Enum.CameraType.Scriptable
workspace.CurrentCamera:Interpolate(game.Workspace.Head.CFrame,game.Workspace.Head2.CFrame,0.5)
script.Parent.Humanoid.WalkSpeed = 0
local keyX = "j"
local key0 = "k"
local key1 = "q"
local key2 = "w"
local key3 = "e"
local key4 = "r"
local key5 = "t"
function press(key)
	key = string.lower(key)
	if key == keyX then
		script.keyXpressed.Value = true
	end
	if key == key0 then
		script.key0pressed.Value = true
	elseif key == key1 then
		script.key1pressed.Value = true
	elseif key == key2 then
		script.key2pressed.Value = true
	elseif key == key3 then
		script.key3pressed.Value = true
	elseif key == key4 then
		script.key4pressed.Value = true
	elseif key == key5 then
		script.key5pressed.Value = true
	end
end
function lift(key)
	key = string.lower(key)
	if key == key1 then
		script.key1lifted.Value = true
	elseif key == key2 then
		script.key2lifted.Value = true
	elseif key == key3 then
		script.key3lifted.Value = true
	elseif key == key4 then
		script.key4lifted.Value = true
	elseif key == key5 then
		script.key5lifted.Value = true
	end
end
mouse.KeyDown:connect(press)
mouse.KeyUp:connect(lift)

A local script runs only on the client. Changes to the client are not replicated to the server unless Filtering Enabled is off. The reason this works in studio play mode is because in play mode, the client is also the server. In server test mode the client and the server are separated. Changes to one client will only affect that one client and not the server or other clients. To answer your question of how to make the client effect the server, you could use a RemoteEvent. I would suggest firing the event every time one of those values changes. On the client, you should call

event:FireServer()

And the server should wait for this to occur using

event.OnServerEvent:Connect()

Further documentation on RemoteEvents can be found here. If you need more assistance, feel free to contact me on Discord (Nitrousoxide#3667)

If my answer solved you problem, please remember to mark it as correct.

Pressing keys on Local scripts work because local scripts are local, they handle user input. The server doesn’t have a keyboard or mouse, or does it?

No. The clients do have a mouse and keyboard (unless they’re on console or mobile lol).

You use a server script when the changes you want to make are for all the players, and all the server. For example, changing the colour of a part. You’d want the entire server to see it. Not just one player.

Seeing your client code, you’re using Mouse.KeyDown and Mouse.KeyUp, which are deprecated. You’re also using :connect when it’s :Connect. Use UserInputService to get user input. I will provide an example.

Do keep in mind that keys in UserInputService are Enum values, meaning you cannot access it with strings.

If you wanted to get input from user pressing E, you wouldn’t make your variable like this:

local E = "E"

but like this:

local E = Enum.KeyCode.E

function onkeypress(input, chatting)
    if chatting then
        return -- if plr is chatting while pressing our key we will end function
    end
    
    print(input.KeyCode.Name) -- print name 
end

game:GetService("UserInputService").InputBegan:Connect(onkeypress)