I mac and TP link issue

Hi all,

I am really desperate and I dont know what to do anymore.

The situation

I have replaced my old D-link wifi router with a new TP link TL-WR841ND

The router is set with the settings from my ISP

so far so good.

I have a windows laptop, Macbook pro, Imac and I phone

all of them connects and have internet using the wifi except the I-mac with OS X 10.7.5

If I connect the cable to the router and use ethernet it is working no issues.

I have tried everything that I found over the net

New wifi name, manually set IP, address reservation from the router, changing channels, reset router again, all from scratch, and no no no

It just does not giving me internet via the wifi only on that nacine.

If I connect to other wi fi router - no issues but with this one

If I leave the DHCP to automatic, it gives me another IP that is not in the range of the router:

The router is 192.168.2.1 - If DHCP is automatic either it does not give IP at all - errorWi-Fi does not have an IP address and cannot connect to the Internet.

or Wi-Fi has the self-assigned IP address 169.254.250.22 and will not be able to connect to the Internet.

And still cannot connect me.

Please give me any further recomendations so I can use my I mac wirelessly

Thank you