Configure RUTXR1 with GPON Fiber Internet

Hello,

We have a RUTXR1, the SFP port of which we have outfitted with a Zyxel GPON SFP module (PMG3000-D20B) to use the router with a fiber connection.

We were able to configure the module successfully in the SFP port and it internally shows status 5 which is active state. However we dont get any internet from it likely due to incorrect configuration. The fiber connection also works with another router so that is unlikely to be the issue.

We tried configuring it on wan6 like wan1 but without success. We also tried disabling wan1 but nothing works.

Can anyone give me a hint how to properly configure that thing for internet access ?

Turns out we needed to configure VLAN 7 and PPPoE as that is required by
Deutsche Telekom.