Still using data instead of wifi?

[BronteLad]

My wife and daughter have a lumia 630 and both phones are set to only update software when connected to WiFi. However I have discovered that both phones do a regular update at midnight using data allowance rather than the WiFi which remains on at all times. I have a 635 set up the same way which doesn't experience this problem. The data usage varies from a few Kb to 100+ mb on some days.
Can anyone tell me what might be going on here?

 

[rogersmart]

I also has the same problem with my lumia 630. I have to turn off the auto updates option to save the mbs. Otherwise, it will empty my internet pack. Phone cannot even connected to WiFi after being turn on all the times. It really annoyed me sometime. Anyone please help.

 

[anon(9152079)]

Try going in Settings -> cellular + SIM -> For limited Wi-Fi connectivity -> don't use cellular data.