LG G4 weak network with china LCD module
 

What the miracle is ? When changed LCD module with frame very low network.In countries area there is no network at all even 2G.
TX is very low.

When I put back genuine broken TX power is 100% what the problem may be?
All contacts and antena is the same.
LCD frame has no any antena !

What the secret problem ?

LG G4 H815

It might be because of the frame material diferent. And the metal on the new dispaly might cause the signal interference. You might add the foam between the display and antena. To see whether it act better. If it is ,you could think about to replace the frame.