my nokia 920 has a problem conecting to my modem

[Windows Central Question]

it was fine untill i tried to change the battery myself since t and when im go mhen it has had a new case arial and port and charging cable replaced it seen a bit better but wiil only conect if i am in the same room as my modem and when i go into the next room it drops to 1 bar then eventually drops out any ideas guys ? HELP i have another 920 but i just love this one and will gladly pay to get it fixed but who where in melbourne au