Switching SIM cards causes trouble with saving pictures and data

Currently I am using two SIM cards: SIM1 VodafoneDE in 4G mode and SIM2 T-MobileUS in 2G. For data I mostly use VodafoneDE. Whenever I go abroad (outside Germany) I use my T-MobileUS for data. Then I go to settings and mobile connectivity to switch VodafoneDE to 2G so I can use T-MobileUS in 4G. However lately I discovered that I get bad reception on the T-MobileUS SIM if I don’t switch them physically in the back.
Ever since then I couldn’t take any pictures with my camera, couldn’t download anything from What’sApp (messages, pictures etc), or sacet anything on my phone/SD card. Many apps stopped working. My phone often slowed down to a point where it rendered itself useless. Random reboots occurred about twice to five times daily. Today, two weeks after coming back from my trip I switched the SIM cards back again. Then, when everything worked fine again, I realized, that switching the SIM cards had caused these bugs all along. (Untill then I was under the impression, that my memory card was broken/had to be rest).
Consequently, I will never physically switch my SIM cards again. But how can I get better data reception abroad with my SIM card #2 ?

Could there be a problem with your SIM2 T-MobileUS card?
Perhaps it’s to old or it has wear and tear?

There could be a problem with the compatability of Fairphone and T-MobileUS. I don’t think it’s a defective SIM card though: I had it replaced about 1 year ago and it works fine if I switch phones (i.e. HTC One)

I can only think of the procedure getting the software all mixed up. Yes, all this switching is done by software, no need at all to physically switch cards.

Maybe keep a slightly different procedure when switching via software.
Like switching off one card while changing the others network and reboot at some point too.
Just my idea to this.

This topic was automatically closed 182 days after the last reply. New replies are no longer allowed.