The smartphone system sends data to the Dexcom server, where that data is made available for reports. To receive this data, the smartphone needs to be connected to the internet and have the Dexcom Mobile CGM app running. Data is displayed in Dexcom Clarity about 3 hours later. This means that with a smart device system, the most recent data you view in Dexcom Clarity is at least 3 hours old.
The Dexcom receiver requires connection to a computer to upload the data periodically. If you use a smartphone part of the time and a receiver part of the time, then Dexcom Clarity needs data from both to provide accurate statistics.
It is possible to use both a smartphone and a receiver to provide CGM data. If you use a smart device part of the time and a receiver part of the time, then Clarity needs data from both to provide accurate statistics.