(1) Check to see if DHCP is turned on in speedstream 4100 router. If not, turn on the DHCP function.
(2) Connect to the Cisco Console and ensure that all ports are in the same VLAN.
(3) Ensure that all your computers receives IP address automatically from the router.

To test each equipments, replace Cisco Switch with the small 4 ports hub/switch.

If everything works fine with small hub/switch, it is obvious that the Cisco Switch is having issue.

If the problem persists with the hub, check the router setting - make sure that DHCP is turned on. If DHCP is turned on, check computer ethernet settings.

....


Do all step 1, 2, & 3 and let me know what happens next.

Cheers!