No Email over WIFI, but everything else works

I purchased a new Docsis3.0 cable modem with 802.11 and dual Wifi. It's N/AC compatible for my Time warner Cable service. I have successfully connected my Iphones and Ipads and can get Itunes, Internet, texting, etc. all working fine via the wifi over the device. However, I cannot receive emails. When I try to update my mailboxes, it just sits and the little wheel just spins around saying updating. Every once and a while, a few email headers will download, but I cannot retrieve the rest of the email. Only when I disconnect the wifi on my device and go back to cellular, can I get my emails.

I have even had TWC look at the modem settings, and they are no help. I assume that it must be a modem setting, as i had no issues with my email on any Apple device in my home until the installation of this new cable modem/WIFI router.

Any thoughts?? I am at a loss!