How to make a realistic and smooth elevator using PrimaryPartCFrame?

Hello! I'm trying to make a moving elevator using for my game (both lobby and game) and I found this script in a question. I tried it myself and it did work, but when I test it out I keep glitching out of the map, the elevator is glitching, going up and down for no reason at all, and randomly teleports up and down while moving. I'm finding a solution, or better, a different code that will look good in my work. Here's the code:

Server:

local TweenService = game:GetService("TweenService")

game.ReplicatedStorage.GoUp.OnServerEvent:Connect(function()
    local Time = time()
    local Total = 5
    local Model = workspace.ElevatorWorking
    local Start = Model:GetPrimaryPartCFrame()
    local End = workspace.clone1.B.CFrame
    while time() - Time <= Total do
        local TI = TweenService:GetValue((time() - Time)/Total, Enum.EasingStyle.Quad, Enum.EasingDirection.In)
        local CFrame2 = Start:Lerp(End,TI)
        Model:SetPrimaryPartCFrame(CFrame2)
        wait()
    end
end)

game.ReplicatedStorage.GoUp.OnServerEvent:Connect(function()
    local Time = time()
    local Total = 5
    local Model = workspace.ElevatorWorking
    local Start = Model:GetPrimaryPartCFrame()
    local End = workspace.clone1.A.CFrame
    while time() - Time <= Total do
        local TI = TweenService:GetValue((time() - Time)/Total, Enum.EasingStyle.Quad, Enum.EasingDirection.In)
        local CFrame2 = Start:Lerp(End,TI)
        Model:SetPrimaryPartCFrame(CFrame2)
        wait()
    end
end)

Client:

local btnA = script.Parent.A
local btnB = script.Parent.B

btnA.MouseButton1Up:Connect(function()
    game.ReplicatedStorage.GoDown:FireServer()
end)
btnB.MouseButton1Up:Connect(function()
    game.ReplicatedStorage.GoUp:FireServer()
end)

(A is floor 1 while B is floor 2)

Thank you!