Help With Antenna Or Motherboard Problem With 3g Reception

[kirev]

Year and a half ago my wife dropped her Mi 4 (3G) in water. It worked until like two months ago and it stopped charging. In a service they replaced the connector and battery (i had a replacement ready). It works good, BUT, on Macedonian Telekom (Deutsche Telekom owned) 3G network it does not work any good any more (it worked just fine for two years). If I put a VIP SIM card it works good, but my wife's SIM is on Macedonian Telekom network and cannot change it

So, I have a theory that either the motherboard is faulty (water, corrosion, time...) OR the repairman that replaced the connector and battery did something to the antenna and it is disconnected or something.

How to check both?

Thanks upfront guys

EDIT: IT'S THE SAME WITH THE PHONE CALLS AND INTERNET. Forgot to mention

 

[dogiex]

Year and a half ago my wife dropped her Mi 4 (3G) in water. It worked until like two months ago and it stopped charging. In a service they replaced the connector and battery (i had a replacement ready). It works good, BUT, on Macedonian Telekom (Deutsche Telekom owned) 3G network it does not work any good any more (it worked just fine for two years). If I put a VIP SIM card it works good, but my wife's SIM is on Macedonian Telekom network and cannot change it

So, I have a theory that either the motherboard is faulty (water, corrosion, time...) OR the repairman that replaced the connector and battery did something to the antenna and it is disconnected or something.

How to check both?

Thanks upfront guys

Have you checked that the APN settings are 100% correct?

 

[kirev]

Have you checked that the APN settings are 100% correct?

Totally. But the problem is with the phone calls, too