The network is good for NetFlix, and Google Chrome. However, for WeChat, it just appears as "connecting" and never receives messages when using cellular data.
When connected to WIFI, everything works as expected on WeChat.
My workaround for this is: (1) turn your personal hotspot on; (2) get another phone (ios or Android) to connect to your iPhone's hotspot.
This workaround solved my problem, as I can receive WeChat messages using cellular now. However, I hope Apple/WeChat professionals notice this issue and fix this bug in the coming update(s).