SM-G781N won't connect to 4G/5G, only works in 3G

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Gandora42

Member
May 3, 2016
16
0
Samsung Galaxy S20 FE
hi

i got the phone from korea, the problem is when connecting to 4G the phone would lose internet and calls then lose the network, i get a message saying "failed to register to network (15)" but if i forced the phone to connect to 3G then it works fine. here's what i tried to fix the problem :

  • turning off the mobile network then turning it on
  • resetting the network settings
  • removing NR Whitelist
and none of them fixed the issue. there's a korean menu in the service mode, but i didn't miss with it. i have attached screen shots of the software information and the korean menu in the service menu.
 

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  • korean settings.png
    korean settings.png
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  • software info.png
    software info.png
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  • service mode.png
    service mode.png
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allday5850

Member
Apr 16, 2019
13
5
Who provides your service? Have you tried going into network settings and APN and see what that says
 

allday5850

Member
Apr 16, 2019
13
5
If it is a Korean phone and you aren't in Korea and it is locked into the network then you won't be able to get service somewhere else I don't think