404 error while graphql access throught AT&T cellular network

I made a react app to access mongodb atlas through graphql.
The app worked fine under my wifi network. It accessed MongoDB atlas and brought data.
However, the problem happened when I run the app in a cellular network.
It failed to access MongoDB with 404 error code.
I tested the app with my iPhone Safari. WIFI was okay, but cellular network failed.

I also tried to open https://realm.mongodb.com/api/client/v2.0/app/${APP_ID}/graphql from iPhone safari.
WIFI showed this error
“no authentication methods were specified”

Cellular showed this error
“cannot find app using Client App ID “xxxx””
It is so weird but it happened.
Why WIFI access and Cellular access are different?

I am using Xfinity for WAN and ATT for cellular networks