Several factors can cause the app to disconnect, freeze or just generally not perform as expected.
When using the app please ensure you have a full data signal of 4G or 5G or a Wi-Fi signal as the Horizon app works just like WhatsApp. It does not eat into your mobile minutes, but if not using Wi-Fi this will be using the data from your mobile data tariff. There are always firmware updates being pushed and there are new apps on the horizon.