I have this server script in ServerScriptService and I tried in regular Roblox but it doesn't send me anywhere when I run the game but it prints "Running" once
while true do
print("Running")
local TS = game:GetService("TeleportService")
local Players = game:GetService("Players")
local code = TS:ReserveServer(8357468682)
local players = Players:GetPlayers()
TS:TeleportToPrivateServer(8357468682,code,players)
end

2 comments
I think the script crash ;-;. You didn't even put a cooldown
Just like what @AProgrammR said, it is possible that you just crashed the script by doing while true do, meaning an infinite loop; therefore throwing an error because of exhaustion. Try putting a delay/cooldown