Are you sure the 8-port switch was just a switch ? As you have not provided any other details, I am making a guess that the old 8 port also was the router, or had some functions you are now missing. Try putting the 8 port switch back but put it between the new 24 port and the Internet, and leave all the workstations connected to the 24 port. See it it then works. Then have a look at the configuration of the 8 port and try to work out what it is doing. The function shoudl be able to be done by something else, the Internet router perhaps.
If you need more help once you have done these checks, please post back here, with as much extra information as you can.