On the top bar of your POS app, you can see whether you are online or offline. When your status is offline, the red bar will appear.
If your tablet is temporarily offline, it is possible that you have unsynchronised transactions. You can recognise these transactions in the 'Transactions' page - they will have a red triangle next to them. This means they are only on your device, and not on our dashboard/server.
To synchronise them, you have to:
Make sure your tablet is connected to the internet (online)
Refresh your transactions by going to Settings > Account > Refresh transactions
You'll get an alert that transactions can't be synced, but in the background they will start uploading.
P.S. Countr will always remain fully operational, offline and online. You can still make transactions when you are offline and sync them to your dashboard when you are back online.