|Check to ensure the cable is good. If you have another cable, try it. If the issue goes away, then you had a bad cable.|
If it's not the cable then it's either your network interface on your computer or the port the other end of the cable is plugged in to. If the device your computer is plugged into has more than one port try a different one. If the problem goes away, it was the port. If it doesn't go away, then you've now narrowed it down to the network interface on your computer.
Check to ensure your network interface has the most recent driver. If it does, then it seems likely it has a hardware issue which means you'll likely have to replace it.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.