Signal gone down here too. I'm in Italy, where i was getting 4G now it's 3G and where the signal was bad (1 bar) now i can't get any at all.
Switched for the Spigen Slim Armor (i think verus iron shield case is the best looking and classy case for LG G3 but i can't stand the signal issue)
Just for information...to all the people with my same experience, have you got the model with the antenna cut or the plain one?
Same here dude... Got the iron shield, returned it for the slim armor. I like it way better and I don't have the cut out