A large organization has been notified that their wireless infrastructure is end$-$of$-$life and will no longer receive security patches. The IT manager has implemented the steps necessary to test and schedule the change. The technicians implementing the upgrade have been unable to complete the entire task over a weekend, leaving several outdated access points connected. The outdated access points will not communicate with the new wireless controller, preventing several wireless clients' access to the WLAN. Which of the following BEST describes the oversight that caused the lost connectivity?

a$.$

Legacy application

b$.$

Dependencies

c$.$

Service restart

d$.$

Restricted activities