yoda99

    Model: SM-G935T

    Android version: 6.0.1

    Basedband version: G935TUVU2APD7

    Build number: MMB29M.G935TUVU2APD7


    Bug #1 - S7 Edge WiFI Battery drain bug


    S7 Edge

    • On LTE radio only battery drain is about 0.3% to 0.7% per hour with no active use of the phone.
    • On turning on WiFi battery drain goes to 10% to 11% per hour with no active use of the phone.
    • On turning on Airplane mode to shut down LTE, followed by turning on WiFi, usage is still 10% to 11% per hour

    This has been tested on two S7 Edges and both phones seem to have the same issue. "Keep WiFi on during sleep" feature is set to Never to reduce battery usage.

     

    Samsung S6 SM-G920T on Android Marshmallow comes in at around 5% to 6% per hour when on WiFi. Why is it that the S7 Edge with a bigger battery is burning more than twice the battery on WiFi? The S7 Edge phones go from 100% to 0% in about 550 to 580 minutes pretty reliably with zero active use and WiFi on.

     

    Bug #2 - S7 Edge WiFi calling shuts down WiFi.

     

    WiFi calling is turned on. Turning on airplane mode, followed by turning on WiFi so LTE radio is off, but WiFi is on. WiFi calling registers and you are able to make calls. WiFi stays up. Then when you make a call using WiFi calling, the call rings and connects, then about 10 to 40 seconds later, the WiFi is automatically turned off and the call drops. After a delay of about a few seconds (between 3 to 5 seconds), WiFi is automatically turned on again and connects to WiFi Access Point. WiFi calling registers again with the IMS system and phone indicates WiFi calling is ready. As long as you don't make calls, the WiFi connection remains up. When you make a call and the call connects, the WiFi automatically turned off after about 10 to 40 seconds, causing a disconnect and WiFi is again turned on again after a small 3 to 5 seconds delay.

     

    When the phone is removed from Airplane mode so that LTE radio is turned on, WiFi is also turned on and WiFi calling registers with the IMS server. At this point when a call is made, the call is connected over WiFi calling and the call continues with no issues.

     

    Samsung S6 SM-G920T on Android Marshmallow has no such WiFi issues with the same test setup.

     

    This behavior is repeatable on two S7 Edge phones multiple times, across 5 different WiFi AP vendors and types and signal levels.

     

     

    What is the procedure to raise a bug report with T-Mobile and Samsung? I'm very surprised that TMO and Samnsung both missed this during QC.

      All replies

      • tmo_lauren

        Greetings!

         

        Thanks so much for the thorough post and information. This is not something I have seen other reports on, but I am happy to follow up and see what we can find. Before reaching out to a business partner who may have a better understanding of if there is anything to do from here, have you already tried a reset on the devices to see if that resolves the problem?

         

        -Lauren

          • yoda99

            Hi Lauren,

             

            I've tried the usual clear cache, reset to factory, change SIM, change mobile operator, etc. The problem with the WiFi battery drain can be replicated reliably. I'm not the only one with this issue. A web search produced the result below which shows that this problem has existed on the SD820 USA version since the phone's release.

             

            Wi-Fi Battery Drain discussion | Samsung Galaxy S7 Edge

             

            As for bug #2 WiFi calling, I will try matesny's suggestion of booting into safe mode and try repeating the test again. I've tried all his other suggestions of Bluetooth off, wipe cache, etc. That the phone switches WiFi off and turns it on all by itself during a WiFi call is very weird behavior I have never seen before on any other smartphone.

             

            Putting the phone into Airplane mode, enabling WiFi and using WiFi calling is a requirement as the phone can switch to cellular connection when the WiFi signal has issues or gets weak. Switching off cellular radio is a requirement when you travel internationally so you don't get charged for calls that switch to cellular without your knowledge.

          • matesny

            Re: S7 Edge WiFi calling and WiFi battery drain bugs

            This is a pretty detailed report to file a formal bug report with Samsung (or Google). I've heard WiFi draining battery with many other S7 and S7 Edge phones but WiFi being turned off, triggered by an ongoing WiFi Call is something new to me. Would you mind booting into safe mode and see if you can reproduce the issue in safe mode? I would also suggest checking the WiFi Direct settings (Nearby Devices) and turning it off if it is on, as well as turning off bluetooth completely.

            Most issues with WiFi calling are actually originate from Router settings or old router firmware but this, since you can reproduce it with many different routers, should be a trouble your phone gets itself into!

            In general, you should try Safe Mode, Reset App Preferences, Wipe Cache and if all else fails, factory reset. It is something to be sought if problem persists after factory reset.

              • yoda99

                Hi matesny,

                 

                I've tried everything you suggested except boot into safe mode for WiFi calling. I'll try that this weekend and post the results of the experiment.

                  • tmo_lauren

                    Keep me updated on the experiment, if it doesn't result in a fix, I'll reach out to our Samsung partner and see if she can help find us some answers!

                     

                    -Lauren.

                      • yoda99

                        Hi Lauren,

                         

                        Could you please go ahead and raise Bug #1 WiFi battery drain with Samsung, using both my input and the link I posted above.


                        The experiment pending is for Bug #2. We can raise the bug independently after the experiment results.

                          • tmo_lauren

                            I typically get a better response if I submit my bugs at once, just so I am not bombarding other teams with emails. So once complete, I'll send the results for both as a follow up and we will see what there is to find!

                             

                            -Lauren

                              • yoda99

                                Hi Lauren,

                                 

                                Flashing the latest update via Odin seems to have fixed the WiFi battery drain issue. I plan on testing the second S7 Edge via an upgrade process to verify the fix. Consider the WiFi battery drain as fixed. If it shows up again, I'll raise it as as a new bug later.

                                 

                                Bug #2 WiFi calling shuts down WiFI bug is now an active bug that can be repeatedly triggered in a reliable fashion. This needs to be raised with TMO QC and Samsung for a fix.

                                 

                                Bug #2 - S7 Edge WiFi calling shuts down WiFi.

                                 

                                WiFi calling is turned on with either #1) WiFi preferred but cellular radio shutoff with airplane mode on and WiFi turned on, or #2) WiFi calling selected to use never use cellular mode and airplane mode off or #3) WiFi calling selected to use never use cellular mode and airplane mode on. WiFi calling registers and you are able to make calls. WiFi stays up. Then when you make a call using WiFi calling, the call rings and connects, then randomly anywhere from 3 to 30 minutes later, the WiFi is automatically turned off and the call drops. After a delay of about a few seconds (between 3 to 5 seconds), WiFi is automatically turned on again and connects to WiFi Access Point. WiFi calling registers again with the IMS system and phone indicates WiFi calling is ready. As long as you don't make calls, the WiFi connection remains up. When you make a call and the call connects, the WiFi automatically turned off after about 3 to 30 minutes, causing a disconnect and WiFi is again turned on again after a small 3 to 5 seconds delay. This problem can be replicated more reliably by calling 611 customer service number instead of a regular phone number. When calling 611 the problem shows up right away within 60 seconds and the behavior of automatically turning off and turning on WiFi can be reliably replicated.

                                 

                                When the phone is removed from Airplane mode so that cellular radio is turned on, WiFi is also turned on, WiFi calling is set to WiFi preferred and WiFi calling registers with the IMS server. At this point when a call is made, the call is connected over WiFi calling and the call continues with no issues.

                                 

                                Samsung S6 SM-G920T on Android Marshmallow has no such WiFi issues with the same test setup.

                                 

                                This behavior is repeatable on two S7 Edge phones multiple times, across 5 different WiFi AP vendors and types and signal levels. I am currently outside the country registered on Orange network in Spain. Not sure if the phone needs outside TMO cellular network to replicate the behavior. That's something QC and Samsung can replicate in their testing. Considering that the S6 has no such issues, I think this is a S7 Edge specific bug. I do have some have some screen shots to share if QC is interested.

                                  • matesny

                                    Re: S7 Edge WiFi calling and WiFi battery drain bugs

                                    Had this all happened while you are in Spain or you had the issue back home as well? Could be router issue if this all happened in Spain, as all the routers you are using must obey Spanish communication laws and there may be some weird law there, the implementation on the routers may be the culprit here! Long shot but it is possible!

                                    I wonder if you can revoke Network Admin privileges from the Phone app. If you look at the permissions of the Phone App, it has an authority to "Change Network Connectivity" and also "Connect and Disconnect from WiFi". Google considers "Network Admin" as a "Normal" permissions class as opposed to a "Dangerous" permission class, which you can easily revoke at runtime.

                                    You probably won't be able to revoke these permissions from the phone app and even if you can, it will likely crash on you at restart, but worth trying.

                                      • yoda99

                                        I had no reason to check WiFi calling in the US, so it took Spain to figure the issue. I even tried it with my Apple Airport Extreme WiFi GW that I lug around, and the corporate WiFi APs both had the same behavior a well. WiFi calling is certainly a bug that persists even after upgrading to the latest image Build number: MMB29M.G935TUVS3APD8 from a few days ago.

                                      • yoda99

                                        Re: S7 Edge WiFi calling and WiFi battery drain bugs

                                        Screen shot of how the call fails within 15 seconds, shuts off WiFi and turns it back on automatically. This is within 15 feet of WiFi router and -50dbm signal. The call fails due to automatic shutdown of WiFi in the middle of the call. Failure of call does not cause WiFi shutdown.

                                        Screenshot_20160525-183003[1].pngScreenshot_20160525-183012[1].pngScreenshot_20160525-183028[1].pngScreenshot_20160525-183103[1].png

                                        Screenshot_20160525-183146[1].png

                                         

                                        Had to redo screen capture again once again to show the automatic shutdown and restart of WiFi causing call failure.

                                        Screenshot_20160525-184027[1].pngScreenshot_20160525-184036[1].pngScreenshot_20160525-184041[1].png

                                      • yoda99

                                        Hi tmo_lauren,

                                         

                                        Any update on the WiFi calling bug escalation to Samsung and TMO QC?

                                         

                                        Regards