Make a VDSL packer forwarder/sniffer using OpenWrt?

I plan to implement a VOIP client for openwrt, and for that I want to analyze the traffic that comes out of an H300s router. What I want to achieve is to make a compartible VOIP client for my ISP that i able to connect to ISP.

In other words I want somehow to use a OpenWrt router as a cheap DSLAM, so I can analyze and replicate the settings that ISP has for voip using my computer. So I can keep on developing without needing to sacrifice my VDSL connection.

The way I try to approach it is:

What I actually want is somehow to demodulate the VDSL traffic, so I can sniff the nessesary traffic that router generates to a specific VLAN. Is there a way where I can repurpose an Old VDSL router as DSLAM?

That's not possible with the current DSL modem driver/firmware, a few days ago the same question was asked: Can i connect two router with a modem via pppoe protocol?

So what alternatives exist on sniffing ADSL or VDSL traffic?
Can I use a used DSLAM? Or I can probe the serial interfaces between chip and CPU?

Also can Lantiq in theory with appropriate software can demodulate a xDSL signal?

For an initial passive sniffing, I just need to demodulate the signal using of of the methods (wikipedia):

Single-line devices implementing the carrier-office part of VDSL2 exist, so you don't need an entire DSLAM. I mentioned a few examples in a similar thread, but note that compatibility may be an issue.

However, since the device mentioned in your first post also has an Ethernet WAN port: Have you tried configuring it to use that port (with an external modem)? If that is possible, it would be a much easier way to sniff WAN traffic.

The ethernet port usually is used to convert the H300s into a vdsl modem so you can piggybag another router. The firmware is locked and in my case I want to reverse-engineer the connections that H300-s does.

So I need the other way around having my own way to emulate the ISP traffic from my computer.

But to be honest I have not done it or I have no idea how I can make H300s to use the ethernet port for WAN. That would aid me a lot for the reverse-engineering.

In order to do so I hafta emulate a FTH connection. In Greece modem's WAN is used either as:

  1. Form FTH connections
  2. As a meant to plug your own router and use the H300s as a modem.

For the first one I need to know which VLANS are used for FTH. Also, IDK if the signal is modulated at ethernet wan port or not. Usually the typical FTH connection is:

(At schema for simplicity, LAN ports are ommited)

So Idk between the H300s - media-converter and wan port whether ethernet segments/unmodulated data are transfered or not.