The question states that all mesh nodes are properly configured, which rules out software or settings-related issues like security mismatches or incorrect mesh IDs. The problem is a failure to connect, which in a wireless network with correct configuration, most commonly points to a physical layer (Layer 1) issue. Inadequate signal strength (RSSI) or a poor signal-to-noise ratio (SNR) due to excessive distance or physical obstructions are the primary causes of link failure. Repositioning the faulty nodes to be closer to other nodes or to establish a better line-of-sight directly addresses this fundamental RF connectivity requirement, allowing for a stable mesh link to be formed.

A. Place the faulty mesh nodes in their own mesh network

This action isolates the nodes rather than integrating them, defeating the purpose of a single, unified mesh network. It is a workaround, not a solution to the connectivity problem.

C. Change the output power settings only on the faulty mesh nodes

This may create an asymmetric link where one node can "shout" but not "hear" replies. Effective communication requires a stable, two-way connection, which this action does not guarantee.

D. Change the security settings on the faulty mesh nodes

The prompt states all nodes are "properly configured." Changing security on some nodes would create a mismatch, actively preventing them from authenticating and connecting to the existing mesh.

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1. CWNP, "CWISA-102 Certified Wireless IoT Solutions Administrator Official Study Guide," 1st ed., 2021: Chapter 6, "The IoT RF Spectrum," discusses the principles of RF behavior, including signal attenuation due to distance and obstructions. While not specific to mesh troubleshooting, it establishes the foundational concept that physical placement is critical for signal reception, stating, "As the signal propagates from the antenna, it is attenuated by a variety of factors... The most significant factor is free space path loss (FSPL)..." This directly supports that moving a node (changing its path) is a valid troubleshooting step for connectivity.

2. Kurose, J. F., & Ross, K. W., "Computer Networking: A Top-Down Approach," 8th ed., Pearson, 2021: In Chapter 7.2, "Wireless Links and Network Characteristics," the text explains that signal strength decreases as the distance between sender and receiver increases. It also details how multipath propagation and interference from objects can degrade signal quality. This core networking principle confirms that moving a device is a primary method to overcome poor signal quality. (Specific reference: Section 7.2.1, "CDMA," and surrounding discussions on signal-to-noise ratio).

3. Akyildiz, I. F., & Wang, X., "A survey on wireless mesh networks," IEEE Communications Magazine, vol. 43, no. 9, pp. S23-S30, Sept. 2005, doi: 10.1109/MCOM.2005.1509968: This peer-reviewed article emphasizes the importance of network topology and node placement. Section III, "ROUTING IN WMNs," implicitly relies on the existence of stable links between nodes, which are a function of the physical RF environment. The survey discusses how connectivity is a prerequisite for routing, and connectivity is determined by factors like distance and interference, which are addressed by node placement.