Dear friend,
My exact problem is that my phone can't connect to the 4G network of Cosmote in Greece. The device was loaded at the beginning with a rom that supports the network of Vodafone - Germany. I had my phone flashed with an unbranded rom, but the problem was not solved. The data speed indicator remains to H, as the software of the device is not able to use the 4G network of my provider. I think that the only solution is to wait until Nokia releases the proper rom for my provider.