Wired Internet Connection Keeps Temporarily Disconnecting

My wired Internet connection periodically disconnects for 2 or so seconds before automatically reconnecting. I use a router. Sometimes, after reconnecting, it will say I have "limited or no connectivity" before connecting fully again a second or so later.

This happens once every half hour or so, although it some times happens more frequently or less frequently.

I have checked the plugs and wires that connect my computer to the router, and they appear to be fine. I have also tried disconnecting the router, leaving it for a few minutes, and reconnecting. After logging out and logging back in, it still has the problem.

Often it disconnects every 5 minutes or so, which disrupts my downloads and often forces me to start over.

It doesn't change anything when someone calls me. It's never disconnected during a phone call.

I doubt it's the router either, as there are a couple other computers in the house on it that do not have this problem.

Any suggestions or help would be appreciated.

Thanks in advance.