ENDIAN Firewall - Logging LAN IPs

Hi all. Not sure how to describe it but I'll try to make it as simple as possible. Hopefully someone will understand what I am trying to explain and help me to solve this.

We have 2 LANs behind an Endian firewall. One of the LAN consist of webservers while the other is our internal computers. Both have different class of IPs, ie. 10.1.x.x for the webservers and 192.168.x.x for the internal computers. We have a CMS system on one of the webservers, which is accessed by both our customers and internal staff.

The problem is that when the internal staff access the CMS system, the CMS logged the firewall IP instead of the internal computer IPs as all access to the webservers goes through the firewall. Is there a way that we can get the internal LAN IPs instead of the firewall IP. FYI, we used PHP on the CMS and we get the IPs using the standard $_SERVER[REMOTE_ADDR] variable.

We are currently using Endian Firewall Community release 2.1 but will be upgrading to the latest release pretty soon. So any help to sort this problem for both releases would be really appreciated.