The most likely cause of the device being accessible via the LAN but not remotely is firewall settings. A firewall is a software or hardware device that filters incoming and outgoing network traffic based on rules and policies. A firewall can block or allow traffic based on factors such as source and destination IP addresses, ports, protocols, and applications. If the firewall settings are too restrictive or misconfigured, they may prevent remote access to the device from outside the LAN. Improper switch configuration is unlikely to cause this issue, as switches are devices that forward packets within the same network segment based on MAC addresses. Switches do not block or filter traffic based on IP addresses or ports. Incorrect IP address is unlikely to cause this issue either, as an incorrect IP address would prevent the device from communicating with any other device on the network, not just remotely. Misconfigured access point is also unlikely to cause this issue, as access points are devices that provide wireless connectivity to the network. If the device is connected via a wired network, the access point is irrelevant. References: CompTIA IT Fundamentals (ITF+) Study Guide: Exam FC0-U61, Second Edition, Chapter 3: Infrastructure, page 95

Role-based access control is the authorization technique that is used to assign permissions and authorize a user based on job title or function. Role-based access control is a security method that defines roles for users or groups and assigns permissions for each role based on their responsibilities or tasks. Role-based access control simplifies the management of user access rights by allowing administrators to grant or revoke permissions based on roles rather than individual users. References : The Official CompTIA IT Fundamentals (ITF+) Study Guide (FC0-U61), page 207.

Failover is a technique that ensures high availability of databases by switching to a backup or standby server in case of a primary server failure. Failover can be automatic or manual, depending on the configuration. Failover can prevent data loss and downtime for critical applications that rely on databases. Reference: The Official CompTIA IT Fundamentals (ITF+) Student Guide (Exam FC0-U61), Chapter 5, Section 5.3, Page 222.

Availability is the measure of how accessible a system or service is to its users. Availability can be affected by various factors, such as hardware failures, software bugs, network outages, natural disasters, human errors, and malicious attacks. To improve availability, organizations can use various methods, such as redundant equipment, disaster recovery sites, continuity plans, and scheduled maintenance. However, not all methods have the same cost-effectiveness.
Redundant equipment is the practice of having backup or spare components that can take over the function of a failed component. This can improve availability by reducing the impact of hardware failures, but it also increases the cost of purchasing, installing, and maintaining the extra equipment.
Disaster recovery site is a location where an organization can resume its operations after a major disruption, such as a fire, flood, or earthquake. This can improve availability by allowing the organization to continue providing its services in the event of a catastrophic event, but it also requires a significant investment in infrastructure, security, and data replication.
Continuity plan is a document that outlines the procedures and resources needed to restore normal operations after a disruption. This can improve availability by ensuring that the organization has a clear and consistent plan to follow in case of an emergency, but it also requires time and effort to develop, test, and update the plan.
Scheduled maintenance is the practice of performing regular checks and repairs on the system or service to prevent or fix potential issues. This can improve availability by reducing the likelihood and severity of failures, but it also requires planning, coordination, and downtime.
Among these methods, scheduled maintenance is the most cost-effective, because it does not require additional equipment, infrastructure, or data replication, and it can prevent or mitigate many common causes of unavailability. Scheduled maintenance can also help extend the lifespan and performance of the existing components, reducing the need for replacements or upgrades.
Reference:
CompTIA IT Fundamentals (ITF+) Certification Guide, page 8
Service Availability: Calculations and Metrics, Five 9s, and Best Practices, section "What is Availability?"