Ivan,
thanks your help! Sad but true: changing the values doesn't do anything. I set the Trigger Interval to 60 secs..
This is an excerpt of my firewall log:
Nov 14 08:13:05 firewall1 : Built inbound TCP connection 272271659 for WAN:192.168.32.99/39342 to LAN:192.168.11.33/7001
Nov 14 08:13:05 firewall1 : Built inbound TCP connection 272271661 for WAN:192.168.32.99/39343 to LAN:192.168.11.33/7001
Nov 14 08:13:11 firewall1 : Built inbound TCP connection 272271672 for WAN:192.168.32.99/39344 to LAN:192.168.11.33/7001
Nov 14 08:13:14 firewall1 : Built inbound TCP connection 272271685 for WAN:192.168.32.99/39345 to LAN:192.168.11.33/7001
Nov 14 08:13:15 firewall1 : Built inbound TCP connection 272271686 for WAN:192.168.32.99/39346 to LAN:192.168.11.33/7001
Nov 14 08:13:17 firewall1 : Built inbound TCP connection 272271690 for WAN:192.168.32.99/39347 to LAN:192.168.11.33/7001
Nov 14 08:13:23 firewall1 : Built inbound TCP connection 272271696 for WAN:192.168.32.99/39348 to LAN:192.168.11.33/7001
Nov 14 08:13:24 firewall1 : Built inbound TCP connection 272271702 for WAN:192.168.32.99/39349 to LAN:192.168.11.33/7001
Nov 14 08:13:24 firewall1 : Built inbound TCP connection 272271704 for WAN:192.168.32.99/39350 to LAN:192.168.11.33/7001
Nov 14 08:13:29 firewall1 : Built inbound TCP connection 272271712 for WAN:192.168.32.99/39351 to LAN:192.168.11.33/7001
Nov 14 08:13:34 firewall1 : Built inbound TCP connection 272271720 for WAN:192.168.32.99/39352 to LAN:192.168.11.33/7001
Nov 14 08:13:34 firewall1 : Built inbound TCP connection 272271722 for WAN:192.168.32.99/39353 to LAN:192.168.11.33/7001
Nov 14 08:13:36 firewall1 : Built inbound TCP connection 272271723 for WAN:192.168.32.99/39354 to LAN:192.168.11.33/7001
Nov 14 08:13:42 firewall1 : Built inbound TCP connection 272272021 for WAN:192.168.32.99/39355 to LAN:192.168.11.33/7001
Nov 14 08:13:44 firewall1 : Built inbound TCP connection 272272027 for WAN:192.168.32.99/39356 to LAN:192.168.11.33/7001
Nov 14 08:13:45 firewall1 : Built inbound TCP connection 272272029 for WAN:192.168.32.99/39357 to LAN:192.168.11.33/7001
Nov 14 08:13:47 firewall1 : Built inbound TCP connection 272272033 for WAN:192.168.32.99/39359 to LAN:192.168.11.33/7001
Any ideas?