Modern smartphones can use a lot of data, and users are often surprised by how quickly their allowance is used. Apps and operating system updates may continue running in the background while connected to WiFi, consuming data without active use. This is often caused by cloud-based apps such as WhatsApp backups, iCloud, Google Photos, or OS updates.
Low Power or Data Saver modes on Apple and Android devices can help limit data usage, but they do not control all apps, often only limiting the device’s own apps or mobile data rather than WiFi.
Because these settings do not cover all apps, it is important to check which apps are using data in the background and to log out (usually via logout.vitalwifi.com) when not using the network in a data-limited environment.
A PDF guide at the bottom of this page explains additional steps to help minimise data usage.