Typical causes of link problems:
- the firewall blocking connections (even if you think you've given permissions to the appropriate items, try disabling it completely for troubleshooting purposes)
- customized network device configurations (such as a static IP address)
- file sharing or other similar applications resident on the system
- having wifi enabled causing a second network connection
- if you have a router connected it may be "managing" the data causing an interrupt
- a malware or virus re-routing network traffic
- a bad ethernet cable or damaged pins in your connector
- a non-supported ethernet adapter