Firewall rules work with HTTPS only


I’m strinngling with the firewall rules in IPFire. I have set the default outgoing ang forward rules both to block and now try to enable all the services that are really allowed to access the outer world to “allow”. This works fine for HTTPS but all other ports/services (like HTTP or JDBC accesses via port 3306) do not work:

The point is: with no rules, there is no access to the outer world, with no service (which is fine).
When I add the HTTPS-rule, outgoing HTTPS-connections work like a charm.
When I copy the HTTPS-rule and change it to work with HTTP, outgoing HTTP-connections do NOT work.
Same for port 3306, it also does not work at all!

So…any idea what could be wrong here?