In order to fix the problem, launch Qualcomm Atheros Killer Network Manager and open the Applications menu:
This will allow you to view network applications and system processes on your PC. Open the DayZ game and try to prioritize the Internet bandwidth. If you can't see the game or if you have difficulties, you can try uninstalling and reinstalling the game. If this doesn't help, press Alt + Ctrl + Delete key combination, open Task Manager and close all unnecessary applications that may use your Internet bandwidth.
If you still have problems, navigate to Start > Control Panel > Uninstall a program, select the software from the list and press Uninstall. Alternatively, you can try using Revo Uninstaller. Even if it can't uninstall the application normally, it will force it to uninstall by wiping out all traces of its presence from the system.