There's a glitch with remote management in Linux, multiple miners from farm start dropping connections after some time (v4.5).
I have a nodejs webgui for monitoring (drowned somewhere in this thread), but i also tested official EthMan.exe via wine and via simple linux tools - it's loud and clear:

nc -zv m10.lev 3333
nc: connect to m10.lev port 3333 (tcp) failed: Connection refused

Restart the miner (no need to restart the machine):

nc -zv m10.lev 3333
Connection to m10.lev 3333 port [tcp/*] succeeded!

Miners are barebone 14.04 without iptables.
Please let me know if i need to provide additional info