samsung g925i need help..

good day to all i have samsung g925i network problem,,have indicate the signal bar but we cn’t call it means fake signal….i try first basic solution,try change flex with antena wire from original unit (same unit) but istill same,board is fresh,,

imei is good 35812106068***…
version 5.1.1
baseband version g925IDVU3DOJ6..

PLS help or any idea to solve this problem..i want to try software first before hardware or repair the board,,but i need any idea or solution pls help me,,tnx in advance..