Cookies must be enabled to use Serv-U

This sounds like an IE issue.  I don't think there is any thing special about chrome & cookies with serv-u.  You could try firefox to make 100% certain.

I'd also try from a second machine to rule out any client side issues.

Is there anything unusual about the CName?  Is your IE set up to do special things (like block cookies for intranet/external sites)?

You could also open the dev console (f12), and see if the Set-Cookie headers are coming over properly.

On your suggestion, I opened up the dev console and took a look.

<form id="CookieCheck">

     <input name="cookieexists" type="hidden" value="false">

I'm assuming this means that it doesn't allow cookies.  I checked another instance I have of the same software but different server and I don't receive this message in IE11 for that instance.

<form id="CookieCheck">

     <input name="cookieexists" type="hidden" value="true">

Not sure why exactly its different as I tried it on the same browser, with the same settings.

That form field might just be reflecting the fact that cookies are having issues.  Since it works via IP, and in other browsers, I still suspect it is something something to do with IE + servername.

Does this other server (that works) have the same type of url?

Does the name of the problem server contain invalid characters (like underscore)?

http://superuser.com/questions/294895/internet-explorer-9-will-not-accept-cookies-from-intranet-sites

You hit the nail on the head bud, that damn underscore I had in my CName was the culprit.  We went ahead and changed it just in case, now everything works normally.  Anyhow, thanks for your help!

cool, good to hear