Your question is Systematic Troubleshooting Approach. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
A user says they cannot connect to a server; what is your systematic approach to troubleshooting? Explain how you would narrow the fault from the client and network path through DNS, TCP, TLS, authentication, and the server process. Name the commands or observations you would use, and distinguish evidence from assumptions. Scope: standard Linux networking and TCP/IP troubleshooting; do not assume a particular application protocol or cloud provider.