Explanation
A site-to-site VPN is a method that creates a secure and encrypted connection between two internet gateways, such as routers or firewalls, that belong to different networks . A site-to-site VPN can secure all traffic between a branch office and its data center by creating a virtual tunnel that protects the data from interception or tampering. A site-to-site VPN can also provide a zero-touch experience for all staff members who work there, as they do not need to install any software or configure any settings on their devices to access the data center resources. They can simply use their local network as if they were physically connected to the data center network.
VNC (Virtual Network Computing) is a method that allows remote access and control of a computer's desktop from another device over a network . VNC can enable staff members to work remotely by accessing their office computers from their home computers or mobile devices. However, VNC does not secure all traffic between a branch office and its data center, as it only works at the application layer and does not encrypt the network layer. VNC also does not provide a zero-touch experience for staff members, as they need to install software and configure settings on both the host and the client devices.
Remote desktop gateway is a method that allows remote access and control of a computer's desktop from another device over a network using the Remote Desktop Protocol (RDP). Remote desktop gateway can also enable staff members to work remotely by accessing their office computers from their home computers or mobile devices. However, remote desktop gateway does not secure all traffic between a branch office and its data center, as it only works at the application layer and does not encrypt the network layer. Remote desktop gateway also does not provide a zero-touch experience for staff members, as they need to install software and configure settings on both the host and the client devices.
Virtual LANs (VLANs) are methods that create logical subdivisions of a physical network based on criteria such as function, department, or security level. VLANs can improve network performance, security, and management by reducing broadcast domains, isolating traffic, and enforcing policies. However, VLANs do not secure all traffic between a branch office and its data center, as they only work at the data link layer and do not encrypt the network layer. VLANs also do not provide a zero-touch experience for staff members, as they need to configure settings on their network devices to join or leave a VLAN.

RJ11 as discussed before was widely used in analog telephony to connect the phone instrument and the cable.

Explanation
If the port is shut down, it means that the switch has disabled the port and is not sending or receiving any traffic on it. This would explain why the network interface's indicator lights are not blinking on either the computer or the switch, and why the user cannot access resources on the network. The port could be shut down manually by the network administrator, or automatically by the switch due to security or error conditions.
References
Port shutdown is one of the common switch configuration options covered in Objective 2.3 of the CompTIA Network+ N10-008 certification exam1.
Port shutdown can cause the network interface's indicator lights to stop blinking2.
Port shutdown can prevent the user from accessing resources on the network3.
1: CompTIA Network+ Certification Exam Objectives, page 5 2: CompTIA Network+ N10-008: Switch not forwarding frames on trunked port3 3: Cable Management - N10-008 CompTIA Network+ : 1.3

AUP stands for Acceptable Use Policy, which is a policy that defines the rules and guidelines for using a network or service. A guest captive portal is a web page that requires users to agree to the AUP before accessing the Internet or other network resources. This is a common way to enforce security and legal compliance for guest users. Reference: https://www.arubanetworks.com/techdocs/Instant_87_WebHelp/Content/instant-ug/captive-portal/captive-portal.htm