Instore requires a network connection when running on the iPad in order to synchronize sales information and employee data.
Typically, your iPad will use its WiFi to connect to the internet. iPads with cellular connectivity such as 3G can also connect to the internet.
If you are experiencing internet connectivity issues or your WiFi is not working, you can troubleshoot those issues with your iPad. Below are links to Apple to help troubleshoot WiFi and internet connectivity issues.