Configuration Port for WAN Passtrough?

Hi guys!

Got my 6450 and i'm pretty new to the Brocade stuff, basic config was no problem till now, but now im a little stuck...

I'm trying to connect my 5G router (Zyxel NR7302, ) to eth1 and pass it trough to eth2 (currently connect to LAN1 on FRITZbox 7530, will be a opnSense Box shortly).
It seems that the whole installation does not like it when the switch inbetween... but i dont get why.

Can somebody maybe guide me in the right direction on how to configurate eth1 and eth2 so that WAN Port (LAN1) on FRITZbox is working again?