After I solved a problem with my iMac connecting to the internet I thought I give a little hint for anyone who has the same problems.
The integrated DHCP Server of the Buffalo Airstation NFINITI WHR G300N V2 doesn't forward the IP and DNS Server correctly to the iMac, so the problem can be solved by changing the settings at the iMac from DHCP automatically to manually.
I set the IP to an IP in the range of the IP-address-pool of the router. Then I set the DNS sever in the network settings to the primary DNS Server as seen in the router diagnosis section. The Search Server in the network settings is the secondary DNS Server in the diagnosis section.
For me this solution worked. I hope i can help anyone with the same problem.
Greetings from Germany.
FloDa
