I have to disagree with armond_in_nj. The FS105 is a straight switch. There is no WAN port nor is there any concept of a "network behind the switch". All ports of the switch are equivalent. It's doesn't matter which port you connect to the ECB2200V or to the PC.
As to why this is not working, I can't tell you. It should work. Does your computer have a gigabit NIC? If so, you might try setting your NIC properties to 100Mbps full duplex manually rather than the default of auto-negotiate. Sometimes auto-negotiation down from 1Gbps doesn't work properly.
Do you have any other wired connections to the router? If so, as a test try placing the switch between the router and a device connected to the router. If you have problems there, your switch is probably bad.