I'm having this problem, and I couldn't find a resolution for it anywhere. Our issue is that when we put multiple ips on the external interface of the ISA server, the Firewall client fails to work correctly.
2 external IPs --- works fine 3 external IPs --- works fine, only when disabling QOS on all interfaces 4 external IPs --- doesn't work at all 5 external IPs --- doesn't work at all 6 external IPS --- doesn't work at all 7 external IPs --- doesn't work at all
Only one Ip is on the internal interface. The firewall client cannot initiate a successfull connection. Let's say I am trying to telnet to port 25 on an external server. With the additional IPs that telnet fails, but with the 3 IPs and QOS disabled it connects without a problem. Basically port connections do not seem to be going through. If there are any current connections prior to the addition of the ips, it stays working. However I cannot initiate any new connections to anything outside the LAN/WAN. The proxy stays working, so the users get webpages etc without problems. We don't use SecureNAT, so I haven't tested it out.