I put intel 6235 wifi cards in my laptops. They work good on any home router. But when at work on a zone director 3000 and 7982's i have to turn both 2.4GHz and 5ghz to 20MHz only and not to auto, and it is still tricky to get them to connect. I do not get the full benefit of dual band wireless. The driver is updated on the card. And i am running the latest firmware on the 3000. I also am running channelfly if that makes a difference and the channels are optimized for compatibility.
Added is a pic from the config of the laptop.