WAN -> raspberry pi 4 compute module & DFR0767 -> ISP router (no network)

Hi People with knowledge,

As you can see it is my first post. Yeah. I will try to be as elaborate as possible. If uncertain or unknown just ask. I will try to answer. But of course I cannot be online all the time ;). I tried to search the forum/internet but could not find anything useful, or at least something that I could understand :unamused:.

I am just getting into OpenWrt. First hardware for it is with the Raspberry Pi compute module in combination with the DFrobot DFR0767 router (2 ports). I am glad to say that I am able to get internet on my hardware. I.e. when I plug in laptop in the second RJ45 port I can browse the internet. Yippie, so far so good.

The problem that I am having is that I want to connect my hardware to the ISP's router (for switch and telephone). But when I connected my second RJ45s to the ISP router WAN or LAN port I cannot get a connection. I can assume some possibilities and tried somethings, but let just say those are a wild guesses of a unknown knowledge.

So my question, can someone point me in a direction or give me some pointers to make my ISPs router have a network connection? Any help is appreciated.

FYI: My ISP uses VLAN (4, 6 and & 7) over glassfiber. My default setting are the bare minimum to get a network connection with PPPOE (VLAN 6).

Kind regards,