Large Posts Not Going Through

Hi, sorry if this was already addressed somewhere – if it was, I couldn’t find it.

I’m running into an issue where large posts are not going through, or, some posts are not going through and the one commonality between them all is that they are quite large. The user has created them, they click “Submit,” and nothing happens (no error message or page reloading).

Is there a way to change the amount of characters that are allowed in a post? Can anyone think of any other reason why posts are not going through? Thanks very much for your help.