The Irrigreen Smart Controller 2 broadcasts its own network for you to connect to, allowing sprinkler functionality if you lose internet. It is also used to transition the controller over to your local Wi-Fi network.
If you aren't able to get connected from scanning a controller, you'll have to manually force it.
Open your phones Wi-Fi settings, make sure you're connected to your home network, hold the red button on the controller for 6-10 seconds.
If your controller has power, you'll see Irrigreen-XXXXXXX displayed as an available WIFI network.
Select that, it will say 'No Internet Available.'
Now go ahead and scan the controller's barcode on the left side. If successful, you'll be prompted to enter your Wi-Fi credentials or, at that point, you can skip.
Should you choose to skip, you can use the controller offline. The Irrigreen network only holds connection for 15 minutes, so it's only used for quick changes and adjustments and then you'd have to rejoin. Once saved, your schedules will still run even if internet is not available.