Sometime if you have multiple IPs with your KVM VPS with us, Cpanel has some issues with the detection of the main IP. This occurs mostly if you have added an additional IP after Cpanel/WHM installation. You can manually change the settings on your server to force traffic over the main IP.
Tutorial below is for CentOS 6+
SSH as root into your server and open the following file: /etc/sysconfig/network-scripts/ifcfg-eth0:0 and comment out the GATEWAY line. Do this for all eth0:X files (one is created for each IP), then restart the network.
service network restart