Network time can be disabled with the toggle at Settings ➔ System ➔ Date & time ➔ Use network-provided time. Unlike AOSP or the stock OS on the supported devices, GrapheneOS stops making network time connections when using - network time is disabled rather than just not setting the clock based on it.v + network time is disabled rather than just not setting the clock based on it. The time zone is still obtained directly via the time zone provided by the mobile network when available.