tl;dr If you don't have network problem, then don't update your xperia U to firmware 184. It has a confirmed problem.
I had the 162 firmware originally installed on my xperia u. The phone ran flawlessly. Then came 184 update which was supposedly a stable update. I read about it and all posts suggested that this update was indeed stable and the network issue had been fixed.
I updated my U on 4th august morning. In the the evening after update to this 184 firmware I'm now facing a network problem. It either shows no service with the network bar full or no service with a cross over network symbol. When there's no cross I can receive calls and messages but can't call or send messages.
I spoke to Sony customer care and they CONFIRMED that this is a known problem for xperia u 184 firmware. I was told to wait for 4-5 days for another update which will fix this. I asked them if it is possible to get firmware downgraded to original one in a service center. They said NO. Even then I spoke to local service center guy and he said that yes they can downgrade the firmware.
What I cannot understand is that if they knew that this firmware had problem then how was I still able to update?? They should have pulled this update form network. Pathetic work form Sony.
