iMac won't connect to internet with ethernet cable

[HillsDavid]

I have a fairly new iMac solid state running 10.9.5. I cannot connect to the internet via ethernet (Wifi works, but is slow where the computer is located).

If I do plug in via ethernet, the Wifi internet immediately cuts out. Other (older OS) iMacs etc. connect to the internet without any problem using the same connection points and cables - it is only my Mac which has the problem.

This is a new problem - the ethernet connection used to work no problem.

It's a pain, because I have to manually plug the computer in by ethernet (and lose my Internet connection) every time I want to use the computer.

Any thoughts? Might it be a port problem on my computer? Is it fixable?

 

[chscag]

The first thing to do is try another ethernet cable. The connectors on them are fragile plus the small thin wires are easily broken and can't easily be seen. Also check the female connector on your router as well as the Mac.

 

[chas_m]

Also likely is the possibility that your router is configured to allow only one machine on its network and needs to be power-cycled if you put "another machine" (connect in a different manner) on it.

 

[HillsDavid]

Yes. That's the first thing I did try. Several times.

 

[MacInWin]

Disable WiFi BEFORE connecting the Ethernet. What is probably happening is that you are being issued two IP numbers by your router, one for WiFi and one for the Ethernet, which then confuses your software.