Service level, indicates the potential maximum.
Bars, indicate signal strength.
Your device, always connects to multiple radio towers.
The radio tower has a limit, it could be channels, it could be bandwidth.
To divide the available signal yo all of the connected devices there are many strategies that can be used.
Wave Division Multiplexing: you get some of the signal, all of the time.
Time Division Multiplexing: you get all of the signal, some of the time.
Etc.
Then there is your device. Many applications can fight over local resources (CPU/RAM/etc) and Network (bandwidth/etc).
It is a complex series of events that is wildly unpredictable even in the best circumstances.
TLDR; If you are experiencing connectivity issues:
– Toggle airplane mode.
– Reboot.
Assuming neither works, it is not your device, and you’ll need a location with better service availability.
Latest Answers