I have tried to replicate the same error on a Windows box, but it seems to be logging in fine on my Windows Arma3 server. Not sure if that's because it's on LAN though.

Can confirm, cannot #login. Server is a Linux box, using same password as found in server.cfg.

Tried restarting/verifying game cache and eventually re-installing the game to a new hard drive but no cigar.

Friend who hasn't updated Arma3 yet to the newest update is able to login fine.
Also tried changing the password, before it was "n00b" now I changed it to "nooblet".

19:31:17 Wrong admin password entered by player: Ferret, playerUID: 76561197999380517, IP: 192.168.1.100:2304.
19:31:25 Wrong admin password entered by player: Ferret, playerUID: 76561197999380517, IP: 192.168.1.100:2304.
19:31:25 Wrong admin password entered by player: Ferret, playerUID: 76561197999380517, IP: 192.168.1.100:2304.
19:31:29 Wrong admin password entered by player: Ferret, playerUID: 76561197999380517, IP: 192.168.1.100:2304.
19:31:29 Wrong admin password entered by player: Ferret, playerUID: 76561197999380517, IP: 192.168.1.100:2304.