this shoiuld work on the 350-24ts, the 350t I am not as sure of, if evey device is on VLAN 1 and the PCs have a PVID of 1 but the router has a PVID of 2, then put the router and only those PCs you want to have access also on VLAN 2
then those PC you want not to have access, cannot hear the router, but all PCs can hear each other I tried to remain child-like, all I acheived was childish.