SMC WGBR14-N 802.11n doesn’t work with my MacBook Pro

I've bought a SMC WGBR14-N router as a replacement for my current Fritzbox. The FB is too slow for wireless with only a small - non replaceable - antenna. I thought I could attach my Qnap 409 to the SMC draft-n router to speed up time machine backups and copying to the NAS.

Reality: The SMC drops connections and doesn't work with either my MacBook Pro nor the MacBook of my girl friend. Most of the time there is a time out when connecting to the SMC. Both with G and N wireless modes. WPA with 802.11g on the Fritzbox works, but not on the SMC router. Connecting by wire gets me into the internet. Next week it's going back to the dealer and I'll try a D-Link or Apple Extreme 802.11n router. I hope for better luck.

(Is there a way to see with which mode a mac is connected to a wireless router?)