Telnet is an unsecure remote access protocol that allows a user to connect to a remote device and execute commands on it12. Telnet does not encrypt the data that is transmitted between the user and the device, which means that anyone who intercepts the network traffic can read the information, including usernames and passwords12. Telnet also does not authenticate the user or the device, which means that anyone can impersonate either party and gain unauthorized access1.

The connection type that the technician should recommend is Satellite. Satellite internet is a good option for people who travel around the world and want to have connectivity while visiting remote camping locations. It works by using terminals which can give you internet access in remote locations as long as they have a line of sight to the satellite in orbit above12.
Since the customer travels to remote camping locations with limited or unreliable cellular service, the best recommendation is satellite internet connection. Satellite internet uses a dish to connect to satellites orbiting the earth, which can provide coverage anywhere in the world as long as there is a clear line of sight to the satellite. This is especially useful in remote areas where traditional terrestrial connections are not available.
References: CompTIA A+ Certification Exam Objectives - 220-1001: 1.6 Given a scenario, evaluate connection type and bandwidth.

If a user's PC is very sluggish, the HDD light on the PC is constantly on without blinking, the PC itself is slow receiving input, and it takes a very long time to load the OS, the HDD has no free space is most likely the cause of these issues. When the hard disk drive (HDD) has no free space, the computer may become slow and unresponsive. The technician should check the amount of free space on the HDD and delete any unnecessary files to free up space.

Allow listing is a security technique that allows only specific IP addresses or domains to access a network or a service. By adding the office IP address as an exception, the company can prevent two-factor authentication from being triggered when users are connected to the office Wi-Fi, since the office network is considered trusted. This way, users will only be prompted for two-factor authentication when working outside of the office, which enhances security.
References: The following web search results provide more information about allow listing and two-factor authentication:
What Is Two-Factor Authentication (2FA)? | Microsoft Security: This article explains the concept of two-factor authentication, its benefits, and its methods.
Change your two-step verification method and settings - Microsoft Support: This article shows how to manage your security verification methods and settings for your work or school account, including how to turn on two-factor verification prompts on a trusted device.
2FA Directory: This website lists all the sites that support two-factor authentication, and the methods they use.