Hello, any news?
same issue for me, same ONT (zte from fibercop).
Same here. Any news about it?
It's strange because when I switched to my spare OpenWRT Router (21.02.0) PPPOE worked on it without any problem.
All time PPPOE = NATIVE IPV6!
Depends on the ISP, like always.
I don‘t use IPv6 but PPPoE works well 
My last TP Link router would always play up and sometimes freeze and then disconnect the PPPoE session. I had a previous ISP look into it but they couldn't see an issue from their monitoring, I tried different firmwares and even had a replacement unit but still had the fault.
So far my Flint 2 has been flawless with the PPPoE and doesn't disconnect randomly.