Why am I unable to gain a shell on a remote system despite finding a vulnerability

Question

I’ve found a vulnerability on a remote system during my penetration testing exercises, but I’m struggling to gain a shell even though I believe I’ve exploited the vulnerability correctly. I’ve tried various payloads and methods, but I can’t seem to escalate my privileges or establish a connection.

What could be the reasons for this issue, and how can I troubleshoot this situation? Are there specific factors, such as firewall settings, IDS/IPS, or patching, that might be preventing me from gaining a shell? Any advice on how to proceed would be appreciated.