The 5GHz band works marginally better now, It drops about 5 min after I leave the room instead of immediately.. I didn't get a chance to look into all of the DD-WRT settings (and play with stuff), but I'll keep looking into it. Hopefully I'll be able to figure out a way to boost the range through the software.
Not an expert...but just throwing it out...
Any chance you have other phones (land-lines) or other devices interfering in that spectrum?
I live out in the sticks, so interference is limited.