Which method can improve the reliability of a network printer?

Installing redundant power sources significantly enhances the reliability of a network printer by ensuring that the printer remains operational even in the event of a power failure. In a networked environment, printers often play a critical role in business processes, and any downtime due to power loss can disrupt workflows and impact productivity. By having one or more backup power supplies, such as uninterruptible power supplies (UPS), the printer can continue to function during outages or fluctuations, maintaining availability for users.

Other methods mentioned, like simplifying user access or connecting the printer via USB only, do not directly contribute to the printer's operational reliability. Simplifying user access may help with ease of use but does not affect how well the printer operates. Limiting the connection to USB can reduce network accessibility, making the printer less reliable in a multi-user environment, where network access would ideally allow multiple users to utilize the printer simultaneously. Utilizing a mutual connection point could imply a shared network device, but it doesn't inherently provide any enhancements to the printer's reliability, particularly compared to having backup power sources.