Ask for an Intranet/Internet isolated communication solution .............

I encountered a little trouble in creating projects for mobile companies,

The Intranet and Internet of mobile devices are isolated. The Intranet can access the Internet, but the Internet cannot access the Intranet.

Our project (BS architecture) is mainly deployed on the Intranet, but some features of the project also need to be accessed by Internet users,

Therefore, the data that requires Internet access is deployed independently on the Internet, but the data that needs to be queried and submitted on the Internet

It must be obtained from the Intranet, that is, the database is only deployed on the Intranet, and there is no database on the Internet.

For example, how can I transmit data to the Internet when an Internet user accesses an Internet web server?