Shoulder surfing is the social engineering attack where an attacker watches a user log in to a corporate system and writes down the user's log-in credentials. Social engineering is a type of attack that exploits human psychology and behavior to manipulate or trick people into revealing sensitive information or performing malicious actions. Shoulder surfing is a form of social engineering that involves observing or eavesdropping on someone's screen, keyboard, or paper documents to obtain confidential information such as passwords, PINs, or credit card numbers. Shoulder surfing can be done in person or remotely using cameras or other devices. Shoulder surfing can be prevented by using privacy filters, locking screens, shielding keyboards, or being aware of one's surroundings. References: [CompTIA Network+ Certification Exam Objectives], What Is Shoulder Surfing? | Definition & Examples | Forcepoint

The most likely reason why only eight cameras turn on is that the PoE switch does not have enough power budget to supply all 12 cameras. The engineer should check the voltage and wattage ratings of the PoE switch and the cameras, and make sure they are compatible and sufficient. The Ethernet cable type, transceiver compatibility, and DHCP addressing are less likely to cause this problem, as they would affect the data transmission rather than the power delivery.
Reference:
CompTIA Network+ N10-008 Certification Study Guide, page 181
CompTIA Network+ N10-008 Cert Guide, Deluxe Edition, page 352
PoE Troubleshooting: The Common PoE Errors and Solutions3

Explanation
The IP address configured on the router interface is 196.26.4.1/26, which belongs to the IP range assigned by the ISP (196.26.4.0/26). However, this IP address is not valid for this interface because it is the network address of the subnet, which cannot be assigned to any host device. The network address is the first address of a subnet that identifies the subnet itself. The valid IP addresses for this subnet are from 196.26.4.1 to
196.26.4.62, excluding the network address (196.26.4.0) and the broadcast address (196.26.4.63). The router interface should be configured with a valid IP address within this range to restore Internet connectivity for all users. References:
https://partners.comptia.org/docs/default-source/resources/comptia-network-n10-008-exam-objectives-(2-0),
https://www.techopedia.com/definition/24136/network-address

A Layer 3 switch will likely replace all the company's hubs when implementing OSPF on all of its network devices. A Layer 3 switch combines the functionality of a traditional Layer 2 switch with the routing capabilities of a router. By implementing OSPF on a Layer 3 switch, an organization can improve network performance and reduce the risk of network congestion. Reference: Network+ Certification Study Guide, Chapter 5: Network Security