Current network setup (public services):
ISP2---- ]----Sonicwall TZ170----[ Exchange 2003 Server, HTTP Server (IIS) /FTP
-Sonicwall TZ170 is setup in failover mode. ISP1 is primary WAN and ISP2 is OPT WAN.
-NAT Rules in place for each ISP (DNS aside, all services available via IP)
When ISP1 is connected (original ISP before failover setup), Everything works fine.
When ISP1 goes down (or is unplugged), web/ftp server is available, Exchange OWA works fine. Exchange SMTP to external recipients fails. You can send mail to internal addresses, but external mail doesn't go and the queue fills up.
All other clients and servers on the network can access the internet when failover occurs and ISP2 is primary with the exception of Exchange. The Exchange server cannot access the web, ping external addresses, etc...
When the primary ISP1 comes back up, internet works fine on Exchange, OWA works, but some Exchange servers crash.
I'm stumped... all responses appreciated....