06-06-2017 07:30 PM
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  1. jeron bernal's Avatar
    Hey everyone, so i currently switched from a normal GS7 edge with T-mobile, to a GS7 edge duos (SM-G935FD) dual sim version.

    after the switch my mobile network has been completely shoddy.

    going in and out of 4G, sometimes i have to switch on and off mobile data or switch between SIM1 and SIM2 to get data back momentarily.

    i'm wondering what setting or adjustment can i do to make my internet more stable? that and why does it Keep switching which SIM to use for mobile Data?

    i am currently using 2 T-Mobile nanoSIMs, both with unlimited 4GLTE, and i even tried updating the APN settings.

    the service in my house and area are SUPERB when it comes to T-Mobile, so i dont believe its the 4G LTE reception...

    any ideas? or options to help increase my service?

    i've read that you can install a US G935 ROM onto the G935FD and it will still work, but would that help my service connection issue?

    i was hoping rooting would be my last resort, because i have never rooted before.

    if anyone has ANY options for me i'd greatly appreciate it! thanks!!
    04-28-2016 07:19 AM
  2. jeron bernal's Avatar
    Ive purchased a Oneplus 2 to see how the mobile data and dual sim react.
    Mobile data works perfectly on the Oneplus, doesn't auto switch and throw me off the network like the s7 duos does.

    please. i could use anybody's help real bad right now...
    05-04-2016 05:34 AM
  3. jeron bernal's Avatar
    the mobile data still says its connected on the S7 just on a different sim card. but on the status bar, there is no 3g/4g/lte/2g/etc. just bars. an no data connection whatsoever.
    05-04-2016 05:35 AM
  4. chanchan05's Avatar
    Have you checked sim manager? You have to specify which sim the data connection is used from.
    05-04-2016 06:45 AM
  5. Mikecalionline's Avatar
    I have the same with my S6 edge duos after upgrading to 6.0.1 marshmallow. The phone keep changing mobile data connection randomly REGARDLESS of what sim I set in "preferred sim card" setting.

    In example pic, in "preferred sim card" setting, I set mobile data as SIM 2. it was fine for awhile until I pick up the phone and look at it again, now my data indicator showed no connection. I pulled down the status from top of screen and saw that my connection was switch to SIM1. Why did my phone mobile data switch to SIM1? The setting still showed data was at SIM2.

    I lost connection because only SIM2 was set at 4G. SIM1 was set at 2G and my stupid phone change mobile data connection to SIM1, hence it couldn't get any data connection on SIM1 over 2G.

    This random switching is really RANDOM. There wasn't any time interval or if I send MMS text on SIM1 or anything. it just complete random. I even try to set preferred data at SIM1, but then my phone will randomly switch to SIM2.

    Anybody know what to do to stop this random switching mobile data to different sim?
    Attached Thumbnails Shoddy Galaxy S7 edge duos mobile data SM-G935FD-screenshot_20160509-133814.jpg  
    05-11-2016 02:04 AM
  6. stardomains's Avatar
    I have a Note 5 Duos and am having the same issue!!! I want and have SIM 2 as being the mobile data but after awhile something changes it to SIM 1 mobile data like the picture above shows and all of a sudden I have no data connection. This was not happening before the Marshmallow update. I have to toggle the settings like 5 times to get it working again. Could it be an app that is causing this? It looks like an issue with the OS upgrade if you ask me. Any solutions?
    05-21-2016 08:58 AM
  7. aabhep's Avatar
    i have a same issue with my Galaxy S7 edge duos with random data switching. Any ideas how to fix this issue ?
    05-22-2016 09:38 AM
  8. stardomains's Avatar
    i have a same issue with my Galaxy S7 edge duos with random data switching. Any ideas how to fix this issue ?
    Some guy in another forum said backup, clear the cache, and do a hard reset..... don't do that! I tried and it took hours getting everything back together and ofcourse it didn't work. We need an OS update for dual sim Marshmallow models fast!
    05-22-2016 10:47 AM
  9. meyerweb#CB's Avatar
    If you put the SIM in slot 1, and set that to be the default, does it randomly switch to 2?
    05-22-2016 12:38 PM
  10. stardomains's Avatar
    If you put the SIM in slot 1, and set that to be the default, does it randomly switch to 2?
    No. Just the other way around. Mobile Data that is. Voice and Text are still on SIM 1. Mobile Data is set to SIM 2. And all of a sudden the notification area switches Mobile Data to SIM 1 and all data connections are broken(cannot reach the internet). Yet in SIm Manager settings it still says Mobile Data is SIM 2. Just like the screen shot the fellow posted above.
    05-22-2016 01:13 PM
  11. aabhep's Avatar
    i've used default settings for data and changed sim cards back and forth, same result- data connection randomly switches. it looks like it switches when default connection is very poor, and does not return to the default one. however when one of the slots is completely disabled data connection is steady.
    if there would be away to disable just data on one of the slots and leave voice ant text ON, but i haven't found a solution for that.
    05-22-2016 02:27 PM
  12. stardomains's Avatar
    The last few days have been fine and I also got an OS update today on my Note 5. No problems since. Maybe it is solved?
    05-29-2016 05:11 PM
  13. Chamunaptra's Avatar
    No way it is solved.
    I am from the middle of Europe and thinking about buying G935FD. But from what I hear here I am starting to be a little dubious. If there is a problem the first one to make an update will be Google and that will be within months. More terrible thing will be Samsung that need to take the Google update and make an update for their phone - that takes about 6 months if you are lucky. If any update will be available, it will be at the end of the year (and that is only if Google knows about this problem which means that at least a couple of thousand people need to report it).

    UPDATE:
    Just found out that there are many more people having problems and it is definitely the update to android 6 (as seen here: 10 Common Nexus Android 6.0 Problems & How to Fix Them)
    05-31-2016 02:18 PM
  14. aergern's Avatar
    No way it is solved.
    I am from the middle of Europe and thinking about buying G935FD. But from what I hear here I am starting to be a little dubious. If there is a problem the first one to make an update will be Google and that will be within months. More terrible thing will be Samsung that need to take the Google update and make an update for their phone - that takes about 6 months if you are lucky. If any update will be available, it will be at the end of the year (and that is only if Google knows about this problem which means that at least a couple of thousand people need to report it).

    UPDATE:
    Just found out that there are many more people having problems and it is definitely the update to android 6 (as seen here: 10 Common Nexus Android 6.0 Problems & How to Fix Them)
    Your update with that 10 common Nexus Android 6.0 issues makes no mention of dual sim card issues cmd+f (on the mac) finds 1 dual reference in the whole page. Also, Samsung has put out several updates since that "article" was published.

    Anyway. My question for folks is this. I have a work phone (AT&T) with unlimited data and my TMO personal phone which also has unlimited data. If it's switching to the strongest signaled sim card then this would probably not be an issue for me. Would it?

    Also, the original post and one further down have 2 sim cards from the same provider ... might I offer that Android and this phone specifically can't quite differentiate between what sim card is preferred as they are connecting to the same towers and maybe Android is having it's routing confused because they are the same carrier sim.
    08-10-2016 09:50 PM
  15. copajoe's Avatar
    I also have the same problem
    Samsung Galaxy S7 Edge Duos.
    when I first purchased it I had 2 T-Mobile chips in it and the internet would switch randomly or just switch off. Then I pulled one T-Mobile chip out and put in an ATT chip. It seemed to fix the problem BUT I do not use ATT

    I live in Brazil and use TIM as my local carrier but also keep the T-Mobile sim to get texts from the US.

    Now this wont work. The data will not work when I have both sims switched on.

    When in Brazil, TIM is in the Sim 1 card slot. If both chips are on, Internet switches to sim 2 but the T-Mobile chip does not even have internet available on it!

    If I switch off sim 2, internet works on sim 1

    Today, I arrived back in the states. Tried to get T-Mobile Internet on Sim 2. NOPE, it switched to TIM which does not work in the states.

    Tried turning sim 1 off and it still did not work. I actually had to REMOVE sim 1 (TIM) chip to get the T-Mobile internet to turn on.

    WTF? if they cannot get this right, it was a complete waste of the extra $150 I paid for this (over the single sim version).

    DOES ANYONE KNOW WHAT TO DO????
    08-30-2016 11:29 PM
  16. copajoe's Avatar
    I have seem to found that it is T-Mobile sim card related. does anyone have this problem who is NOT using a T-Mobile sim card?
    09-12-2016 12:08 PM
  17. Dualuser's Avatar
    I can't give answers yet but I can give hope. I got my G935FD from Amazon two weeks ago and I've been trying to use it with my two T-Mobile SIMs (work & personal) in USA. Getting the same problem i.e. involuntary change of mobile data to the SIM that's SUPPOSED to stay on 2G. Cannot see any logic or pattern in how/why the switch happens. Rebooting the phone restores the situations for a few minutes, until the pull-down menu shows the data connection is with wrong sim again.

    First I was desperate that the phone wouldn't support all the frequencies that is was supposed to support after all, but by monitoring the phone in service mode (dial #*0011#) I already learned that it does indeed use all the T-Mobile LTE bands, i.e. 2, 4 and 12. The exact frequencies don't appear to be what I read they should be but I don't think this got anything to do with the problem at hand. The other sim is on 2G 1900 MHz as it's supposed to.

    Now the hope part: I started playing with the APN settings (Settings>Mobile networks>Access Point Names) last week and finally got the phone working. Both sims maintained their righteous settings for many days and over the weekend. The unfortunate part is that I don't know what exactly was wrong with the original settings, and the autistic part of me couldn't live with that. So today I erased all the existing APN settings, in order to have only the very correct ones for both sim cards. I deleted the whole list of factory settings and created new ones from scratch. Did the sims continue working? Did they f**!

    Knowing that the solution is out there somewhere, I try to be patient this time. I have sim2 deactivated and sim1 with internet is working just fine. I'm letting it be like this overnight and hope that the phone and the network become friends and don't want to forceswap the connections once I turn on sim2 tomorrow. If no help, then I continue playing with the APN settings again. Meanwhile it would be nice to hear if anyone can explain what all the APN settings actually mean?

    I have "APN type" set as 'default,mms,supl' but does it matter that which order these are in? Should the 2G-sim have exactly same APN settings? Should the 2G-sim not have mms setting? Should the 2G-sim use IPv6 or v4? Should the 2G-sim APN be 'fast.t-mobile.com' or 'epc.tmobile.com' or something else?

    Cheers
    09-12-2016 05:21 PM
  18. mjtaryan's Avatar
    I have a Note7 Duos with Android 6.01 and it has the same or similar problems as many of the comments. At this point, the main problem is that I cannot get mobile dafa on one of the sim cards -- a specific provider -- when both sim cards are installed. When only the "non-connecting" sim is installed it connects fine, but not with two sim cards. I've swapped slots without success. It doesn't matter which slot the offending sim card is in or what the settings are. I thought it might be the way Samsung has the dual sim cards set up, but with what I've read here, I'm beginning to think it is a problem eith Android 6.

    As for the hybrid issue, it seems to me that a slight modification of the hardware would solve that issue. If the tray was a little deeper so that both an SD and a sim would fit in slot 2 plus turning the sim card reader upside down so that the sim cards were put in the tray upside down -- it could solve the whole problem.

    My solution to the either SD or second sim problem is store the data that would have gone onto an SD on a USB 3.0 256gb flash drive. Seems to work.

    Now if Sansung would give us 256gb on internal storage (SD 0), then most of the need for external storage would be removed.
    09-12-2016 09:02 PM
  19. mjtaryan's Avatar
    Someone needs to write "A Guide to APN". Not me, though; I don't know what all that stuff means either. And what APN settings can be left at "Not Set"?
    09-12-2016 09:10 PM
  20. Dualuser's Avatar
    I just want to update that I have had no luck with fixing the problem with APN settings. I no longer believe that those got to do with it. I found another forum with clearly more educated discussion about the same problem (but no unambiguous solution there either):

    S7 Edge Duos data connectivity problems | Samsung Galaxy S7 Edge

    Same as 'copajoe' who also appeared on the other forum, I'm not qualified to try the firmware updates that the other folks are talking about.

    But unlike 'copajoe', I don't believe that T-Mobile is the cause for the problem. At least not necessarily, even if most people involved seem to have T-Mobile as a provider. I believe that it is simply because most people writing in these forums are from USA and in USA there is only two GSM carriers (TMO and AT&T). Other big ones use CDMA and are not at all compatible with "international" unlocked phones.

    I am getting desperate. The first posts about the matter are soon six months old and Samsung still hasn't fixed it. It would be nice to read how others are doing, even there were not any good news. And if anybody reading this has their phone working, can you please please let us know your current settings, especially APN. Screen shots would work best.

    Cheers
    09-14-2016 10:32 AM
  21. aggiez28's Avatar
    I m having the same type problem.
    when i take my tmobile sim out of the phone the phone works fine. this is very annoying
    09-21-2016 09:19 PM
  22. JOC2016's Avatar
    Firstly I hope you have all worked out that a 3G data signal or better is only available in the first (bottom) SIM tray. The top SIM can only receive a 2G (not data) signal - at least this is my understanding. Now, I completely get the neither SIM is working phase. I got one of these dual SIM S7 FD edge phones directly from the far east (to my knowledge). I despaired in first 2 months of ownership as neither SIM would work even a single bar consistently in any location and I could scarcely even call or text let alone mobile data (previously I had both SIMs in separate phones without reception issues in either) so I downsize to nano sims (same plans) put in the S7Duo and neither had even phone or text capability. However, I stuck with it and the phone took a big Android update in late August this year. Since virtually the moment that finished installing both SIMs miraculously came to life and I have had no problems since. So in short you will still only get data capability in one SIM - so pick the one you want it on and put in the bottom slot of the caddy, and make sure you have downloaded this android update that has existed in the UK since late August (I think I've heard it described as a security update?? I don't know a lot about Android, but I know that last update fixed every problem I had with both SIMs). I hope this helps someone.

    Once both SIMs are working the phone is fabulous - stick with it - the Android update is the solution IMO - you just have to get hold of it, but even with it you only get data on ONE of the SIMS - that is the way the phone is currently designed - I spent ages researching this online when I had SIM problems!
    09-22-2016 02:03 AM
  23. Hansgraff's Avatar
    Firstly I hope you have all worked out that a 3G data signal or better is only available in the first (bottom) SIM tray. The top SIM can only receive a 2G (not data) signal - at least this is my understanding. Now, I completely get the neither SIM is working phase. I got one of these dual SIM S7 FD edge phones directly from the far east (to my knowledge). I despaired in first 2 months of ownership as neither SIM would work even a single bar consistently in any location and I could scarcely even call or text let alone mobile data (previously I had both SIMs in separate phones without reception issues in either) so I downsize to nano sims (same plans) put in the S7Duo and neither had even phone or text capability. However, I stuck with it and the phone took a big Android update in late August this year. Since virtually the moment that finished installing both SIMs miraculously came to life and I have had no problems since. So in short you will still only get data capability in one SIM - so pick the one you want it on and put in the bottom slot of the caddy, and make sure you have downloaded this android update that has existed in the UK since late August (I think I've heard it described as a security update?? I don't know a lot about Android, but I know that last update fixed every problem I had with both SIMs). I hope this helps someone.

    Once both SIMs are working the phone is fabulous - stick with it - the Android update is the solution IMO - you just have to get hold of it, but even with it you only get data on ONE of the SIMS - that is the way the phone is currently designed - I spent ages researching this online when I had SIM problems!

    Has anyone figured this out? Still having the same issue on my S7.
    10-25-2016 12:54 PM
  24. steven8934's Avatar
    Has anyone figured this out? Still having the same issue on my S7.
    Hello Everyone,
    I have the Samsung Edge 6 plus duos (SM-G9287).
    I have the same issue. I have TMO and ATT sim cards. I have tried to switch the sim locations and it still randomly switches but only on my ATT sim. Whenever the ATT sim says 3G, on the drop down menu the Mobile Data says it is on the TMO sim. But if I go into SIM Manager Mobile Data is still set to ATT so when this happens I switch the Mobile Data to the TMO sim then I switch it back to ATT sim to make it work again because ATT sim 3g will never revert back to 4g until I do the above process. But it only happens on my ATT Sim which is annoying. So I am mostly on my TMO sim for Mobile Data. Hopefully the Nougat update fixes this issue and hopefully arrives Q1 2017 or even earlier.
    11-07-2016 08:35 PM
  25. jc914's Avatar
    I have the same device, (G935FD) and i'm on T-mob, but I only have one sim and not having any issues. I would not put a G935T, on a G935FD, you will probably brick it. Try taking SIM2 out and see what happens. There are some chats about replacing the existing modem with a US modem.
    01-19-2017 01:53 PM
31 12

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