Phone has an option to turn on/off 4G internet.
On one phone 4G is working, but on the second one when I turn on 4G internet stops working.
It shows H+ signal (on other shows 4G) and upload is working (up arrow is blinking) but download doesn't.
I have disassembled the phone to check if antenna is bad, but I don't see any issues.
Is this a hardware or software issue?
Maybe I can replace antenna.
Today I noticed that I don't get calls even though the signal is full on both SIM cards.
I tried to make a call, and it doesn't ring, just silence.
That happened couple of times. 4G was turned on.
I turned on/off Airplane mode, and it worked again.
If I turn off 4G, then phone works better and internet is good most of the time, though is just H+.
Swap SIM cards between the two phones. If the problem follows the SIM, Maybe there is an issue with your carrier or SIM card. If the faulty phone still has an issue with the working SIM, then it's not a SIM or network issue.