Only getting around 30Mbps Download on Premier

Model Name: SB6121
Vendor Name: Motorola
Firmware Name: SB_KOMODO-1.0.6.14-SCM01-NOSH
Boot Version: PSPU-Boot(25CLK) 1.0.12.18m3

What model modem do you have? Probably Cox needs to adjust the service code on your account for the new DOCSIS 3.0 modem.

Motorola SB6121

First thing I notice is the SB6121 is only a 4x4 channel modem, so you will never get 8 downstream channels with it. For that you would need the SB6141. I think the main issue is your missing a certain code on your account that unlocks the full speed of DOCSIS 3.0 modems. If a moderator doesn't respond here soon, I would suggest calling in and asking them to change it.

Ok, the 4x4 bit makes sense.  Will give them a call and see what happens if no one stops by.

Thanks for your help!

It's a wireless-N router so it should be good to go.  

I just got off the phone and direct connection to the modem is, in fact, getting me 110Mbps.  Connecting back to the router it goes right back down to the 30Mbps.  So...I guess it's a router issue.  

Using Intel(R) Centrino(R) Advanced-N 6235 wi-fi adapter

@modestermix Before completely dumping the blame on the router I'd suggest testing with a different N device and/or testing your laptop on another N or better router to see which way the problem goes.  Something else I thought of too, make sure you're not using WPA-TKIP encryption as how it's only compatible with wireless-G and will force your wireless link rates down.

Looks like I've got WPA2/WPA Mixed mode for my wireless security?  Should that be changed?

WPA vs WPA2 doesn't matter, as long as it has AES encryption and not TKIP. Looks your card can do 802.11a/g/n 2x2 and 2.4/5 GHz, so that "should" be enough, but there are alot of variables. This article does a pretty good job describing it, specailly on page 9.

You also want to check your radio (Mixed, G only, N only, etc) and match it to your needs. If you don't have any G devices, and don't plan on getting any, its generally better to put the router on N only. 

:;Edit:: Forgot to add link. Oops

Messing around with settings on the router (Set security to WPA2 Personal, 5Ghz, wireless-N only) I've juiced it up to 61 Mbps on my Mac.  Certainly an improvement.

My Macbook Air is now showing up to 82Mbps (with my kids watching Netflix!) but other devices (PC running Win7, Samsung Galaxy S3) are still in the 30-40Mbps range.  Guess I'll read up on what the specs are in the Air's wireless adapter...