IPhone Won't Connect to Secured Wifi

Question

I recently got a new iPhone 4 and I am unable to connect to my secured WiFi network with it. I can connect to it just fine with my laptop, old droid phone, iPod touch. I can also connect to it if I remove the security but not if the security is on. I've looked all over online, tried everything I've read, even took it into the Apple store where they completely reset the phone, all to no avail. I also brought the phone into a Verizon store, and they were able to connect to a secured wifi hotspot in the store, so I'm going to assume its a problem with my router.
ISP: Comcast Perfromance Cable
Modem: Comcast Motorola SB5120 Cable Modem
Router: Belkin N600 D8 Wireless N+ Router (Model: F9K1102v1); firmware up to date as of today.
I went to this website, plugged in all those settings and still nothing. I simply get "Unable to connect to <Network>". The one setting that I wasn't able to match to those had to do with DHCP. By going to my cable modem's config, I can tell that the DHCP client on it is turned on. The problem is, I cannot change the modem's settings readily through that page (192.168.100.1) and when I turn off the DHCP on my router my laptop has problems maintaining a connection.
Here's some screenshots of the settings, perhaps you guys have better insight/advice/etc. I've been trying to use the 2.4ghz connection for the iPod, I don't use it for anything else so I couldn't care less what the settings are... I just want it to be secured. I use the 5.0ghz connection for my laptop and such.
Here's the Channel and SSID settings... renamed the networks for the purpose of this.
Security Settings
WPS Settings (Honestly, no idea what this does).
Lastly, LAN settings:
If it's a problem with the phone itself, I still am with the 14 day return policy.

Answer 1

I guess I'm stumped other than to say that it can definitely create problems if you are trying to run DHCP on your wireless router if it already enabled on your Comcast cable modem.  You only want one device managing DHCP on your network, normally the one that is the furthest "upstream"; in this case that would be your Comcast router.  I would try disabling DHCP on your router just as an experiment, then power-cycle your Comcast router, followed by your Belkin router, followed by your phone, then see if it connects successfully.  If it does, and when you restart your other devices they connect successfully, I would try to figure out how to solve the problem of the laptop not maintaining a connection.  Perhaps it needs an driver update?