I just want to discuss a particular network problem I encounter just recently, it's actually an additional connection to the router, the cable is just newly bought and crimped from the store.
The problem encountered is when you plugged the cable, network icon indicates a limited connectivity and shows an exclamation point. It took me sometime to trouble shoot the problem, but later I found out that CAT5 cable is not crimped based on standard configuration.
The hard part in identifying the problem is that LAN cable is newly purchased so it's the least you suspect.In case you encounter similar problem described above, try to inspect the connector visually or adjust network connection properties to 10 mbps full duplex(default setup is auto), if PC established network connectivity then it's confirmed that connector was not crimped in accordance to standards.
It is important than you observe proper cable configuration when crimping new connections to ensure a problem-free network.
Standard CAT5 LAN connector configuration: