[Q] 4G not working after 4.3 update topic

Hello everyone,

I have Galaxy S4 I9505 that is unbranded and unlocked, updated with the latest firmware via Kies3. Stock ROM, Knox 0x0.

My firmware info:
PDA: I9505XXUEMKF
CSC: I9505BTUEMK5
MODEM: I9505XXUEMKF
(I checked on sammobile and its UK BTU firmware)


I am from Croatia using T-mobile as a carrier. Problem first appeared right after the first 4.3 update was released via Kies3.
The problem is that when I select LTE in Network mode options it doesn't connect to 4G, the icon only shows H+ in a 4G area. If I leave it running in LTE mode, after a while the mobile data will shut down, signal will drop (like it resets) and after a few moments it will work again. My mail or whatsapp messages for example will arrive 10 - 30 min later. This will repeat over and over until I turn it off in Network mode and select WCDMA/GSM only. Everything was working fine prior 4.3 update.

Also I hope there is a solution that doesn't include flashing custom modem files or anything that voids my phone warranty.

Thank you,
Skyward