For 10 years, this has worked. There has been no updates, firmware or configuration.
3 location site to site VPN. At the main site is an Exchange server that requires port 443 for Activesync.
It's been working.
Suddenly yesterday at lunchtime, client complains about lack of emails on their phones.
Port 443 is closed. I log on to a on site workstation and check, the server is reporting fine. OWA and Microsoft-Server-Active-Sync respond fine on IIS. It's not a server issue.
Reboot RVS4000 router - port 443 opens - briefly. For maybe 15 seconds, and then closes again. In that 15 second interval, everything works, active sync phones included.
After a bunch of testing, ensuring that the router isn't touching 443 (remote management is off), the port forwarding is set OK (I'll note here that all the other port forwards work fine).
Finally I work out that if I turn OFF IPS, the port forwarding of 443 works. But the site to site VPN's drop off. If I turn ON IPS, we go back to having VPN, but no port 443 forwarding.
Replaced the router with a spare, uploaded the config, same issue. Running 1.3.3.6
It's not the server (yes, done all the firewall checks and so forth, server is behaving fine. While IPS is OFF, everything port 443 dependent works). It must be the router, but I can't see where.
