C# client does not coneect with server, but ua expert connects well.|OPC UA Standard|Forum|OPC Foundation

I'm a student who wants to create a digital twin environment using opc ua.

I purchased an opc ua server from a robot company. And Through this, i want to extract robot data and receive it to unity.

So I strated the first step, extracting data from the opc ua server, but i got an eerror right away.

The problem came when i was trying to extrat data from the server using a c# script.

The error message said connect error. So I tried other scirpts that I found on the internet, but the same error was repeated.

Also the C# scripts I used first was from where I bought the server, so it doesn't seem to be a problem wih the script.(because the company said it worked well when they tried it with same c# script )

The irony is that the server works well when connected as an UA Expert.

This is my first time using OPC UA, and I can't find the cause of the problem, so I want to ask for help.