XZ1 dropping network signal

[SOM3A115]

my XZ1 keeps dropping network signals, i alrdy have a wifi problem as many XZ1's, but today losing network signal is the new problem to appear, 

[MarlonUk1]

most xperia in my experience would rather connect to higher band as opposed to the strongest signal. it might be that your device went from full bar 2G band to 1 Bar 4G band, however if there is associated problems try to perform a software repair using Xperia Companion