Somehow I don't get it completely....
Referenced page says:
IPv4 FastTrack is active if following conditions are met:
* no mesh, metarouter interface configuration;
* sniffer, torch and traffic generator is not running;
* ****removed****no active mac-ping, mac-telnet or mac-winbox sessions****removed**** restriction removed in 6.33;
* /tool mac-scan is not actively used;
* /tool ip-scan is not actively used;
So fasttrack should be active, but why are the mangle rules affected?
How I understand the fasttrack is, that a new TCP (or UDP) connection runs through the firewall, but then the established connection bypasses the firewall. This gains performance.
My mangle rule should establish a connection to the different router, then when established everything could run through fasttrack (bypass the firewall).
Problem is only that it does not work. everything works fine, when the fasttrack rule is disabled, When I reenable it the packets go to the default router