cannot get LTE communication with S4mini plus (i9195i)

[Fezrf]

Hello

Here is my issue: I buy a second hand S4 mini plus (i9195i - serrannoveltexx) for its compact size and by considering the simple usage I make of my phone. So far I do not use so much data so I don't care about used network, but recently I start using more data and I notice I never get LTE. I change carrier because I was thinking LTE-cover was the problem, but not. I still have no LTE. So below, is more or less everything I tested:

at beginning, I was few months on stockrom. Then I go to LineageOs 14.1 (thank to dev for the work). In both case I'm almost sure I had no LTE (I checked APN and 4g/3g/2g enable in network menu. And I start to check LTE-cover of each carrier . And I very start to check band used by the different carrier).
I change carrier and I check APN once more : still no LTE.
I come back to stockrom (just in case) : still no LTE
I switch SIM card : my sim card in Oneplus One get LTE and sim-card of my friend do not get LTE with my phone. (So I try copying manually the exact same APN : not working)
I try to flash old stockrom and let OTA update make the work : no LTE
I make necessary to have CSC=XEF as I am in France.
I try flash with pit-file and re-partition.

At the end, the best thing I succes to get was H+ (and for some reason I have it when I clear and restore the NV in 'service menu'), so :
-I contact samsung and they recommend me to go to one of their after-sales office.
-I contact my seller and he tells me that LTE works in germany.

Does someone has an idea how to solve this issue ? something that could block LTE ?

Next step I have in mind :
-I read some topic where double-flash within wipe and clear factory could help (but I have the feeling that will not work because it is more or less what have done to change CSC)
-I would check the activated LTE bands (but in 'service menu', I find a LTE band hexa-value that meet with explanation of binary description (another thread in XDA - thanks to people who write this tuto))
-I am considering go back to LineageOS but 15.
-I am considering to change LTE antenna (this is part of middle frame - I notice if I enable Data when i have 'service menu' opened, the phone seems to looking for LTE first, so I am not sure this is only SW problem ... do you think it is possible that only LTE part of such a SystemOnChip could die ?)

Thank by advance for your help
Best regards

 

[IronRoo]

Hello

Here is my issue: I buy a second hand S4 mini plus (i9195i - serrannoveltexx) for its compact size and by considering the simple usage I make of my phone. So far I do not use so much data so I don't care about used network, but recently I start using more data and I notice I never get LTE. I change carrier because I was thinking LTE-cover was the problem, but not. I still have no LTE. So below, is more or less everything I tested:

at beginning, I was few months on stockrom. Then I go to LineageOs 14.1 (thank to dev for the work). In both case I'm almost sure I had no LTE (I checked APN and 4g/3g/2g enable in network menu. And I start to check LTE-cover of each carrier . And I very start to check band used by the different carrier).
I change carrier and I check APN once more : still no LTE.
I come back to stockrom (just in case) : still no LTE
I switch SIM card : my sim card in Oneplus One get LTE and sim-card of my friend do not get LTE with my phone. (So I try copying manually the exact same APN : not working)
I try to flash old stockrom and let OTA update make the work : no LTE
I make necessary to have CSC=XEF as I am in France.
I try flash with pit-file and re-partition.

At the end, the best thing I succes to get was H+ (and for some reason I have it when I clear and restore the NV in 'service menu'), so :
-I contact samsung and they recommend me to go to one of their after-sales office.
-I contact my seller and he tells me that LTE works in germany.

Does someone has an idea how to solve this issue ? something that could block LTE ?

Next step I have in mind :
-I read some topic where double-flash within wipe and clear factory could help (but I have the feeling that will not work because it is more or less what have done to change CSC)
-I would check the activated LTE bands (but in 'service menu', I find a LTE band hexa-value that meet with explanation of binary description (another thread in XDA - thanks to people who write this tuto))
-I am considering go back to LineageOS but 15.
-I am considering to change LTE antenna (this is part of middle frame - I notice if I enable Data when i have 'service menu' opened, the phone seems to looking for LTE first, so I am not sure this is only SW problem ... do you think it is possible that only LTE part of such a SystemOnChip could die ?)

Thank by advance for your help
Best regards

Some older Samsungs eg Note 1 had reception problems due to poor connection (possibly oxidised contacts) that could be fixed by simply tightening the screw a fraction that secures the pcb or antenna so it was grounded (from memory) properly, though of course it could be your actual antenna that has failed. (possible cleaning contacts might be worth a shot if tweaking screw doesn't fix)

(or modem/baseband issue if software, try flash again or try another version, backup your baseband radio settings first with twrp or an app)

edit: also try reset network settings before paying for new antenna (edit: though suppose flash with pit etc should have done this)

 

[Fezrf]

Hello,

Some news on the topic:

I try to tighten the screw and I also try to clean LTE antenna contacts : I use very very thin sandpaper (usually used to polish) to be sure there is no oxidation

I also make the mistake to erase all EFSs and EFS_Backup
Reminder : in service menu (*#0011#), then 'UE Setting & Info' / 'Setting' / 'System' / 'NV backup test' / 'Erase all EFS 1/2/3' => So never do this if you have no backup
After this, I lost my IMEI... no way to restore it with IMEI tool... What a pity because I was hoping to only set my IMEI in order to test with completely clear EFS. Finally I restore my IMEI thank to my very first TWRP backup (thank to TWRP team that it works for me because it seems not always the case)

I try 3 times consecutive reset factory : 2 in recovery and 1 in settings.

I try to activate new LTE band but it seems that as I am in StockRom, update is not properly done.
In fact just after the work with QSPT and QXDM, I can find the nez band in service menu (*#0011#), then 'UE Setting & Info' / 'Setting' / 'System' / 'LTE band & CA combination. but after reboot I lose it. Probably I'll make the work one more time after coming back to LineageOS.

One last thing I want to try is going in front of 4G antenna and check signal power seen by the phone but I'm thinking this is not the true problem. I explain:
service menu (*#0011#) start to show Basic network information and if I force LTE_only (in service menu), I can observe these information. strange thing I see are sometime state goes to 'TAU_init' (and also 'deregistr' or 'register'). Some other time MCC-MNC goes to 151515-1515. I have the feeling the phone is trying to connect but something goes wrong and I do not know what...

if someone has an idea, I am still looking for.

Best regards