I have a Cisco 2821 router that sits behind a PIX firewall. When this router is using a PAT IP it can ping and telnet outside public IPs thru the firewall with no problem. Recently I added a static NAT entry so I can telnet to this router from the outside. I made sure that there was an ACL entry on the PIX permitting telnet traffic to the router's public IP but I was not able to telnet into the router from the outside. After double-checking my work and doing some testing I found that the minute I create a static NAT entry for the router I lose all connectivity to the outside from the router. This includes pinging and telneting out from the router that works when the router is using a PAT IP but not when the router has a static IP. What can be causing this?
BTW, there are other devices, like Windows servers that are working successfully with static IPs thru this firewall. The problem seems isolated to the router. I also tried different public IPs to NAT to the router but the same situation persists.