Just to post the end of the story that can be useful for someone else.
After a while the support contacted me and solved my issue or better my issues beacause were two problems.
- Fp2 issue. Even with a working 4G sim card in my FP2 it doesn’work, so the support suggested to register again the sim card on the network
Go to Settings > More > Mobile Networks > Network Operators
This is set to Choose Automatically, though if you refresh the list you get to see all available operators. It can take a while before it shows all operators. But when you are here choose the one that is from your network provider.
After doing that my phone begun to work on LTE band with my wife’s sim card.
- I call my carrer help desk and after a while they enabled my sim to 4G even it was already enabled…but it worked
