Xperia z5 dual lte problem

[Heakee29]

Hi

I have a Xperia Z5 Dual running Android 6 stock rom. It works fine with 3g sim card. When I put 4G sim card and set network mode to "LTE only", there is no signal. When I use mode " LTE prefered/Hsdpa/Gms", the signal is 3G. I put that sim card to a Samsung tablet and 4g works. I took a factory reset but nothing changed. Please help me how to solved it. 

Regards.

[Uliwooly]

@Heakee29

Is your phone compatible with your carrier's LTE bands? also, some carrier networks need to enter the IMEI number to their data base and enable LTE on that device. 

[Heakee29]

My carrier's LTE bands is 1800 Mhz.  My Xperia Z1 phone works as well, but Z5 can not. How can I test whether 4G antenna (or component devices)  is woking?