Uh... here is my 2 script and nothing work (I mean 2 different script so I can try)
local players = game:GetService("Players")
local player = players.LocalPlayer
local character = player.Character
local humanoid = character:WaitForChild("Humanoid")
humanoid.HealthRegeneration = false
game.Players.PlayerAdded:Connect(function(player)
player.CharacterAdded:Connect(function(character)
local Humanoid = character:WaitForChild("Humanoid")
humanoid.HealthRegenerationRate = 0
end
end