NVG599 Wifi performance issues

I was initially really impressed that AT&T sent this router out proactively, to replace my previous Gigapower router.  The move was supposed to improve WIFI performance, but the experience has been just the opposite.  On both of our iphones, as well as the wife's laptop, we experience frequent timeouts, and slow performance.  After trying several things, including doing a channel scan, forcing the network to "G" only.  No luck.  

I dug out my old Linksys router, plugged it into an ethernet port, and wifi performance is just fine.  Interestingly, the signal strenth is higher on the Arris unit, but the actual usuable performance is much better on the Linksys wifi.

Any thoughts would be appreciated.