[Galaxy A3, A5, A7, A8, A9 Q&A, Help & Troubleshoot] gabitagabisss:
Hi! I have an A5 (SM-A500FU) bought in Italy last year, Im using it since then in Argentina. With android lollipop I have never had issues with lost signal, no service messages or network not available. But since upgrading by OTA to Marshmallow these problems started. I have looked everywhere but I cant find anything that helps me. Also my service problems are not always present, sometimes I do have signal, but mostly when im out in the street. At home, for example I have no service and "only emergency calls" message. I'm using right now and old Moto XT316 with the same SIM card ( Claro AR) im using in the A5, and it is working fine, recieving network signal ( it is also a new sim card, just in case old SIM was the problem). The thing is I can´t use my A5 because it is constantly losing signal.

Thing I have already tried and didn't work:

- Changing to aireplan mode for a few minutes

-take out SIM card, restart the phone, turn off phone, put sim back in again, turn on phone

-verifiyng the APN for my network Claro Ar was correct, manually searching networks ( At home for example, it only finds Personal and Movistar (sometimes) but never finds Claro ar)

-Doing factory reset

-Reinstalling official firmware (PDA version : A500FUXXS1CPH2; CSC version : A500FUVFR1CPG2) with kies3 ( smart switch gave me an error)

-Flashing the UK BTU ROM ( the old one was from Vodafone Italy, now Phone info app says my mobile operator is 72234, while befor was 722310 which is correspondig with claro ar, what does this mean)

what could be causing this problem???? Im really starting to desperate now...

I read something interesting online, searching for some answers I got to the experience of some guy who had a very similar problem. Short story, his had to change his phone's network configuration in the "radioinfo" menu (or whatever the name of that hidden menu is) with an app named Network and force his cellphone to use only 3g or 2g. Turns out that his phone was trying to use LTE but LTE was not available in his region. This solved his problem. Mi phone can't use LTE here in Argentina because it is Italian, and since I have it it never conected to LTE network (I guess we use different frequencies) So I was thinking maybe my phone is also trying to use LTE but since it won't reach 4g signal ends up with no signal at all, excatly like this guy's phone.

But, apparently I need root access to get to this menu or even use this apps, is that correct?

So, should I root my phone to try that? does that story make any sense to you? Any advice?

Downgrade to lollipop I read is not my best option, also rooting it isn´t , but I'm starting to run out of solutions.

I add this information that could be helpfull:

Product Code : SM-A500FZKUBTU

Original CSC code : BTU

Active CSC code : BTU

PDA version : A500FUXXU1CPH3

CSC version : A500FUBTU1CPH1

Baseband version :A500FUXXU1CPH3

Android version : 6.0.1

Build number: MMB29.A500FUXXU1CPH3

Mobile operator :72234

Also IMEI number seems to be fine, it starts with 35 and matches the one in the back of the phone.

Sorry It is such a long thread!! Thank you very much!!