You could try this,
Factory reset the router, either downgrade to v1.02 or re-send the v1.03 FW file. After sending and the router reboots. Do one more factory reset. USE IE For this.
Go directly to Guest Zone and set up the 2.4Ghz Zone as I listed in my post and see what the result is.
If it still fails here then this unit needs to be RMAd.