I commented that a couple of days ago I started reading the documentation corresponding to the configuration of a private server. I have managed to acquire the necessary information without problems but at the time of extracting the packet length I throw the following error.

https://ibb.co/hKGMWJS
What is the cause of that?
I would appreciate your support
Attached exe in case someone could help me.
https://drive.google.com/file/d/13Rhk4r ... sp=sharing
A big hug
Regards!!