Spitz Plus, setup as PPPOE FTTP main connection, with 4G failover.
Goodcloud shows the 4G Static Public IP address, not the FTTP connection Public IP Address?
Should it not show both, or has it made a preference, as on Multi WAN, ethernet is the Priority connection, and Cellular is fifth in the list?
Generally it shall show your FTTP connection Public IP, as long as it has the Internet access.
Would it convenient to share the device to us for the further verify?
Technical support via GoodCloud - GL.iNet Router Docs 4