You can use your HomeSys system in a place without internet connection, but it will provide only local security functions. Here you can see what functions are available with or without internet connection:
With internet connection
Alert notifications and siren sound
Live video
Backup recorded videos to cloud
Local/remote add new accessories
Scenes and scheduled functions
Remote control of automation devices
Remote check system status
Remote or local arm/disarm the system
Make changes in configuration (ex: alarm delay and partial arm)
Without internet connection
Local arm/disarm the system (from keypad or remote controller)