Are you using a (like GTX or Nitrado) or Self-Hosting ? Are you using mods (specifically ACE or ALiVE)?
If you are running the HC on the as your dedicated server, you will have port conflicts. arma 3 headless client steam authentication failed
headlessClients[] = "127.0.0.1", "your.hc.ip.here"; localClient[] = "127.0.0.1", "your.hc.ip.here"; Use code with caution. Copied to clipboard 2. Update Steam Binaries Are you using a (like GTX or Nitrado) or Self-Hosting