To troubleshoot a network connectivity issue reported by an end user, confirm the user's device model, network type (wired or wireless), and the specific error message, if any. Start by running diagnostics using tools like [Network Diagnostic Tool] to check for hardware faults or configuration errors. If the issue is related to wireless connectivity, assess the strength and stability of the [Wi-Fi Network Name] and check for interference or network congestion. In the case of wired connections, ensure all cables are securely connected, and that the network interface card (NIC) is functioning correctly. If the issue remains unresolved, escalate to your network administrator or service provider for further investigation.