Microsoft working on a fix for data issues with dual-SIM Windows 10 devices

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The recent Windows 10 Mobile Insider Preview Build 14342 brought many fixes for annoying issues, but Microsoft still has work to do for other bugs that have not been addressed yet. Among the many issues Microsoft is working on to fix by the next Mobile build, there is one that prevents Windows 10 phone owners from properly using the cellular data on their devices.

It’s been more than a year since users asked for a fix for this issue:

Microsoft Lumia 640 XL Dual Sim, Problems With Dual Sim. It Seems Dual Sims Blocking My Cellular Data.

When Dual Sims activated:
(First SIM card 3G and second SIM card no internet access)
I opened two websites.
The first one did not allowed me to login AT ALL ( I tried three times and cannot login) and the speed was turned to slow.
The second website allowed me to login but the speed was slow.

When I turn off dual Sims and use only the first SIM (I use only 3G depends on the signal)
Both websites opened fast and I was able to login to both of them without any problem.

There is a problem when dual SIM is activated (dual stand by), however I cannot tell if this is a software or hardware problem.

The cellular data issue on dual-SIM Windows 10 phones is not region or country specific, as one would first imagine, nor does it have anything to do with carrier or signal coverage as another user confirms:

I have the same problem with lumia 640XL DS with Italy operator.

First sim is TIM with 3g activated (2100Mhz), and the second sim il LycaMobile (Vodafone) with no data active, but it’s 2100Mhz too.

With this configuration i have same problems with speed and responsive application.

Let us hope that a fix will be available when the next Windows 10 Mobile build is launched. Otherwise, this issue will become another annoying problem Microsoft took too long to solve.

We are investigating data issues with some Dual-SIM devices where cellular data doesn’t work correctly with a second SIM. Several issues relating to cellular data with Dual-SIM devices have been reported by Insiders with the last two Mobile builds and we’re investigating these reports.

It is interesting to notice how Microsoft downplayed the issue, stating that Insiders reported it with the last two Mobile builds. Actually, users started complaining about this problem back in 2015.