Linux is a 2nd class citizen with these guys. They can't even get the Linux client updated from 1.42, they've teased us with talk a 1.52 version for a few months, but we're not seeing any dev branches updates to help them with testing. Now they have 1.54 version on Windows and no timeline for Linux Battleye support, so a Linux client is pretty much useless for multiplayer.

After additional testing, I was able to get Linux HC to work on a separate (Ubuntu 15.10 on VMware) single core/cpu VM. I was not able to get it to work on the same VM as the server (2 core/cpu VM), even when I used taskset to run both processes on the same core/cpu. It appears that there is a race condition specific to the Linux HC, when running on multi-core/cpu machines.

Encountered the same issue. I was able to get the headless client to connect by making the VM single core. Obviously, not an acceptable solution. I suspect a race condition exists, probably in the handshake.

Additional details: Both the server and the HC are running on a Ubuntu 15.10 VM (running under VMware). I was able to get the HC to connect and FuMS to run correctly, however both processes were running on a single core. When I increased VMs core, the issue manifested.