Dlink dgs 2208 switch

1. the dlink is a switch not a router.  It cannot issue dhcp addresses and many cable modems can't either.  Perhaps you had a dlink 5 port router which can issues dhcp ip adresses.

2. all network devices and the cable modem must be power cycled.

3. attach two computers and give them static ip addresses and try to ping one from the other.

Pls check your connection between the switch and the router,dsl,access point.
2.make sure the gateway router is receiving good signals