SharePoint 2010 wouldn't work on one of the WAN

Ok, our sharepoint link is http://sharepont10 and for some reason it didn't work on one of our WAN site.

A Host(A) record is already added to DNS server for the correct ServerNameand IP address

A Alias(CNAME) record is already added to DNS server for the the name"Sharepoint10"and point to ServerName

we have three site with three subnets

LAN: 10.1.1.X (work)

Site1: 10.2.1.X (work)

Site2: 192.168.1.X (not working) --> The webpage cannot be found

Note: the URL for sharepoint was " http://Sharepoint10.domain.com" and we changed to just "http://Sharepoint10"

I checked the WAN's DNS servers, they are seems matched out. on the 192 site, I ping "sharePoint10" and get reply with the server's IP.

I have  another URL on the same server, is for sharepoint MySite and it actually works no problem:http://sharepointserver:19301/default.aspx

Anyone know why? DNS issue? IIS issue?