STP (Shielded Twisted Pair) cables are used to protect against electromagnetic interference (EMI). The cable distance is not exceeded, as the 26ft (8m) patch cable is within the maximum distance of 100 meters for Cat 6 cables. The patch cables are also plenum rated, which means they can be used in air plenums without emitting harmful fumes. The most likely reason the users cannot connect to the network is that the pinout on the patch cable is incorrect. The pinout is the order in which the wires in the cable are connected to the RJ- 45 connector. If the pinout is incorrect, the data signals will not be transmitted correctly and the user will not be able to connect to the network.