Thank you for your prompt answer
Yes, I deactivated the proxy at all (via WUI). Then I changed settings via setup (comand line) to DHCP. IPfire properly took the settings from my ISP. That’s the reason I find it strange pakfire is still trying to connect via upstreem proxy as no upstream proxy is defined. For me it seems that the "upstream proxy is kind of “hardcoded”, or pakfire takes half of the settings from the former stable release 146.