What key factor should be analyzed on network design maps to troubleshoot issues?

Analyzing the device common to customers affected is crucial for troubleshooting issues in network design maps. This approach allows technicians to identify patterns or commonalities among devices experiencing problems, which can indicate specific faults or misconfigurations. Understanding what devices are impacted can lead to more targeted diagnostics, enabling the technician to focus their troubleshooting efforts effectively.

The other factors listed, while important in their own right, do not provide as direct insight into resolving issues affecting multiple users. For instance, signal strength is important for understanding connectivity problems, but it does not pinpoint which devices are specifically having issues. Length of cabling is a critical factor in network design, particularly for ensuring performance and compliance with standards, but it doesn't highlight affected users. The type of connectors present can affect overall network performance but is less likely to provide immediate insight into user experience issues unless there’s a known problem with a specific type of connector. Therefore, focusing on the common device among affected customers streamlines the troubleshooting process by narrowing down the potential sources of the problem.