Default [Q] Help...10.4.B.0.569 (Swiss) will not connect to 4g

Hello guys im pretty new to this fourm so if theres any rules i violated in this post please excuse me.

My problem occured when i flashed my sony Xperia z T-Mobile branded phone. It had 4.2.2 t-mobile firmware on it so i flashed to 10.4.B.0.569 (swiss) ch ftf and everything was running fine until i noticed that it wasn't connecting to 4g...Only 3g but on the t-mobile firmware it connects to 4g just fine (i reflashed it just to make sure) andi reflashed back to 10.4.B.0.569 and it still said 3g i tryed *#*#4636#*#* and messed with the newwork settings a bit like some other treads recommended and none of then changed it to 4g i even changed the APN because it was set to (which is 3g service and below) so i set it to (the 4g/lte service) i changed it to everything the tmobile firmware apn said and it still didnt go to 4g it just says at 3g i rebooted my phone and luck it just says 3g. Please i need help to get my 4g back i really like the UI in 4.3