No typo. I tagged port 9 of the switch, which is connected to the WAN-Port of the openwrt router. I read in another post (https://forum.openwrt.org/t/solved-vlans-on-ipq40xx-alternative-config-for-fritzbox-4040/41832/3), that on this Fritzbox 4040 the driver is not working good with VLAN and the port 5 (which is the WAN-Port) must be tagged. Otherwise the router is not reachable, after VLAN is enabled.
I also tried to tagg port 10, which is connected with port LAN1 of the openwrt router. But this leads also to a not reachable router.
Matthias