There could be multiple reasons for such a behavior to occur. Without more thorough investigation on your end and a more detailed description it's impossible to provide a good answer. Please take the Tour to learn how good questions are structured.
However, what you're experiencing could be some kind of anti-patching protection, and the network related error suggested it might be related to some kind of server side verification.
Some ideas I can come up with:
- An internal CRC or other code integrity blob (such as a cryptographic hash) is being sent to the server for validation.
- A code integrity check is being performed and validated locally, only reporting the validation failure to the server or falsely reporting there's a network issue.
- Your repackaging does change the application is some less obvious way which damages the application's ability to communicate with the server.
- There's actually a network error, either due to your repackaging or for any other reason.