You IOS + Bluetooth guide
Please note, that in IOS 13 you have an option to manually allow Bluetooth connection of your Apps; Settings > Privacy > Bluetooth (you can check if Equa App has Bluetooth connection). Please check that APP and IOS are up to date. Please note, that you can only pair 1x device to the bottle.
Could you also check your internet connection is stable?
Maybe this video will also help (from 0.53 sec on): https://www.youtube.com/watch?v=jiGdmlLpmKE - hopefully this should resolve your problem.