Users ate moving back into an office that had been vacant for awhile. Ten workstations are hooked up in the office, but one workstation cannot obtain a link with (he switch. A network engineer checks the documentation and cable labeling, and everything is hooked up as expected. The engineer moves the connection lo a different switchport. but a link still cannot be obtained. When the engineer puts a tone generator on (he infrastructure cable, no tone is heard at the far end. Which of the following issues is the engineer MOST likely trying to find?