Minecraft HackClient can't search servers?

I have my own HackClient programmed in Minecraft but if I have Z.b. On my Localhost the testing I can't connect to it because there's always only: "Connecting to the server…" nothing else and the servers in the server list look like this

Can someone help me?

and please do not answer like Zb.b "Hacken ist schiße" or "Why are you chopping" Let that be my concern and this is a platform where you can answer questions from others and help each other.

Hello I've programmed my own HackClient in Minecraft…

CopyPasta? Someone who "programs" something should also be able to debug it. What does the code look like? Are there [hidden] error messages?

Let that be my concern and this is a platform where you can answer questions from others and help each other

Helping does not mean telling you what you want to hear, but telling you the right way to recognize the real problem so that you can solve it.