Samsung S4 mobile data connection issue

[AC Question]

A very puzzle question about this old Samsung S4(SGH-I227M), When Open the data network, top icon show "4G" and Two uplink and downlink flashing, so I have internet access, for just about one or two minutes, The uplink keep flashing, BUT NO DOWNLINK, no internet access as well. I am wondering aloud if hardware connection is a real problem or something else, like software. All other features are normal, wifi, phone call, text.
Eager to hear some opinions.

 

[Tim1954]

I'd try my sim in a different device and try another sim in the S4 to rule out sim card/card reader issues.
Then a chat with the service provider just in case settings have slipped...
A cache partition wipe would be beneficial to start the process....