Wifi Intern (LAN) slow, Internet could me quicker.

Hi all,

I have the following problem. And 3 days of google searching didn't solve the problem.
My iMac is one of the late 2009. And everthing was well in the beginning. Internet was fast and I had no probl

After 3 years the problems started. The Network port stopt working. I can see it in the hardware list and in de network settings.
But it when I plug in a LAN cable, no ip. No warrenty anymore so WiFi was the solution.

Now after some more months and a couple of OSX updates, WiFi is reallys slow. I have a N WiFi network and a fiber internet connection.
The download speed on the iMac is 2.2 mbit. And on LAN it will net even get their. Streaming a SD movie from the intern NAS wont even work.

All other devices in the house works great. The Router is 6 months old. No problem there. Only the Mac.

Can I use an usb tot lan converter. Or an wifi dongle? Or does anaybody know how this can be fixed?

Thanks in advance!

Anne