Why does ajax inside an iframe not work with mobile traffic?

Question

Mobile development

There are many sites.
In each of them inside the iframe.
The iframe sends a request to its host asynchronously.
On computers and on mobile via WiFi - everything works!
If the mobile Internet is on, it does not work!
An asynchronous request is sent, but the response is empty. (on the network or via WiFi, then the answer comes).

Why can this be?

Answer 1

Alternatively, the 3G connection goes through some kind of telephone provider proxy, which cuts traffic according to some of its own rules. For example, he thinks that there is advertising in iframes and cuts the excess to save money.