[CentOS] Need help with an odd issue I am experiencing

>Not a laptop it is a server with dual nics mtu set at 1500, 1 nic directly to the cable modem the other to my lan.

MTU has nothing to do with laptops, it has to do with TCP/IP.
Aside from a previous posters duplex setting (good catch on his part) its
possible that MTU is an issue. Some ISP's do some silly stuff. You
*are* going into a cable modem (which I read as accessing the internet
through some means other than a high-end fiber/etc connection where oddities
wouldn't likely exist:>)

jlc