1. Jeremy Crockett's Avatar
    First here are the details for the hardware and software involved:

    Devices: Samsung Galaxy
    Tab E (SM-T378V) - three (3) devices
    Tab A 2018 (SM-T37V) - ten (10) devices
    Tab A 2020 (SM-T307U) - thirteen (13) devices

    Android Versions: 8.1.0, 10, and 11 respectively

    Carriers: Verizon via 3rd party vendor and Verizon directly

    No SD cards present

    Pre-installed, unwanted apps removed.

    Google Play Store, Google Play Services, and Google Maps are up-to-date.

    All Samsung software is up-to-date.

    All Verizon software is up-to-date.

    Two older tablet versions were previously in-service and functioning as expected until the GPS errors began appearing. The newest tablets are recently un-boxed, set up, and have never been deployed.

    Here is the problem:

    I work in the IT department for a national transportation company at a local division. The county we are contracted with purchased tablets and data plans through a third-party vendor for use with said party's Computer-Aided Dispatch / Automatic Vehicle Location (CAD/AVL) software.

    A few months back, the GPSs in the older tablets (13 of them) began to malfunction. When drivers open Google Maps, there is no blue dot to represent the user location. When a destination is entered, Google Maps hangs with no route suggested.

    Additionally, these units no longer connect via 4G to Google Play or the WWW.

    The Vendor's software requires a specialized APN rather than Verizon's standard "vzwinternet" in order for the CAD/AVL software to work.

    In order to take up the slack in hardware, my company wanted to use 13 of OUR tablets for the CAD/AVL by taking the SIMs from the County-provided tablets and putting them into the fresh, unused tablets.

    Initially, I thought we had succeeded because we tested the CAD/AVL software on the NEW tablets with the OLD SIMs and were able to access Google Maps, the CAD/AVL software and had 4G connectivity to Google Play and Chrome.

    Unfortunately, we happened to test the ONLY tablet out of the 13 that functions properly. The other 12 new tablets exhibit the same connectivity problems that the older tablets had. I took the step of swapping the functioning SIM out with a suspected bad SIM and (as I suspected) the functioning SIM still functioned and the bad SIM was still bad in the swapped tablets.

    It was suggested that I take the new un-used SIMs and test the OLD tablets to see if there was 4G connectivity and GPS functionality. Well, surprise surprise, the NEW SIMs function fine in the OLD suspect tablets with 4G and GPS working as expected. The problem is that the CAD/AVL software does not function because of the specialized APN.

    Now, I have heard that SIMs should not affect GPS functionality. But, given what I have just experienced, SOMEthing is going on, right? Or is there something that I am missing?

    If these 3rd party supplied SIMs do not work in the old OR new hardware, this is a SIM problem, correct?

    Additionally, if our new SIMs work in BOTH the old and the new hardware (APN issue aside) this demonstrates that there is NOT s GPS hardware problem in the OLD tablets.

    If you are still with me at this point, I thank you for your patience and perseverance through this ordeal. If you have any suggestions, if there is something I have missed, if there are more details needed, please let me know because I need to be certain before I insist that the vendor replace the suspected bad SIMs for the County.
    10-15-2021 10:30 AM
  2. B. Diddy's Avatar
    Welcome to Android Central! You mentioned that pre-installed and unwanted apps have been removed -- this doesn't include any system apps, right? The devices aren't rooted? You might want to try doing a factory reset on one of them so that it has all of the apps that originally came with it, in case one of those apps was actually necessary for GPS to work properly.
    10-15-2021 11:36 AM
  3. VidJunky's Avatar
    So if changing to regular SIM cards causes the device to function properly and the SIMs with the modified APN settings are an issue it sounds like there may have been a system or app update that is affecting the use of those APN setting. Perhaps it needs to be updated. So still a special APN, so the app continues to work, but different from the current one.

    Have you contacted the supplier of the SIM cards to see;
    1) if there have been any updates or changes?
    2) are they familiar with this issue and what do they recommend?
    3) are the current tabs still compatible?
    10-16-2021 08:04 PM

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