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1-to-1 NAT Configuration Replies With Wrong Public IP Address

THE PROBLEM:  The current (1-Router/RV220) configuration is returning the wrong public IP address to the Voice Provider - meaning, the Voice Provider is receiving x.x.x.101 instead of x.x.x.100.

ADDTIONAL INFORMATION:  When I create a 2-Router configuration (Cisco RV220 + Netgear N300), the correct public IP address (x.x.x.100) is returned to the Voice Provider.


1)  Comcast ISP providing 5 static IP addresses.  The Comcast SMCD3G-CCR modem/router is configured in "pseudo" bridge mode - meaning, Comcast replaced the D3G's native GUI with a Comcast custom GUI that does not provide for a "true" bridge mode configuration.

2)  Cisco RV220W router

3)  VLAN1 = the Default VLAN (static public IP = x.x.x.101) and is used for the Domain network.  DHCP services are provided by the SBS 2011 Domain server.

4)  VLAN99 = a 2nd VLAN (static public IP = x.x.x.100) for the Voice network.  DHCP services are provided by the RV220.


Obviously, I am doing something wrong but, I can't figure it out - any help would be greatly appreciated.

I have attached some screen views of the RV220 configurations for reference.