My iPhone will not connect to the internet

In short, the problem is that the phone cannot connect to the Internet for an unknown reason, in fact it is not in the apple ID, but the phone itself shows that it is in the account. He has been updated to version 16.3.1, But still there is no access, that is, he cannot log out of his account due to the fact that he does not connect to the Internet, and why he does not connect is not clear

[Re-Titled by Moderator]