Wireless Router and Cards

You probably initially had the wireless router in N-only mode for testing the N adapter. But in order for the wireless G adapter to work, the wireless router needs to be MIXED mode. Problem is, mixed mode will always reduce your performance to the lesser of the two protocols.

My wireless settings are set to 11n Max Speed, not mixed mode. The wireless G cards are still working. It shows on the site monitor that the router is putting out b/g/n signals at a speed of 270.

If your router is supporting b/g/n, that's mixed mode, by definition.

Btw, those speeds reported by site monitor and even Windows are completely bogus. They don't reflect real world, measured speeds. They're simply estimates based on the signal quality. That’s like determining how long it will take you to drive from point A to point B based on the weather; it’s certainly something to consider, but all kinds of other things can happen along the way to impact your time (accidents, traffic congestion, getting lost, etc.). Your actual performance it typically far, far less than those numbers due to interference, transmission errors, etc. My own wireless connection is reporting 54mbps, but is actually closer to 15mbps when measured. So you can basically throw those numbers out the window.