The background to this is my hardware is a samsung J1 running Android 5.1.1.  This was originally sourced from 2D but now I am with Orcon (Spark?).  For some time now I have had WIFI switched off as I do not use all of my monthly data allowance most of the time and I have so much rollover data some expires from time to time.  Moving to Orcon though, the rollover data was lost and I turned on WIFI to minimise data use over the first few months.

The problem I have is that if I power up at home, the handset connects via WIFI and GMAIL and LOGMATE (commercial driver logbook app) work OK.  Leave home though and the WIFI symbol is replaced by the 4g symbol so mobile data appears to be working.  Fire up GMAIL again though and sync fails.  Head back home and GMAIL syncs OK.  Chrome always works (or appears to).  For the LOGMATE app I can force it to stop then run it again and it comes up as 'online'.

My exposure to android and data networks is basic but as I understand it swapping from WIFI to mobile data involves an IP address change but I would have thought that apps should be able to deal with this.  Google search gave no specific results but this problem is difficult for a non-tech such as myself to use the right search words.  I am aware that the J1 is an entry-level device and would contemplate upgrading if there is credible evidence that this would alleviate or fix the ssue.

Any pointers appreciated.