This is the thread I wish I had read last weekend and thankyou to all for documenting a solution - I like the lateral thinking of tagging prior to OPN seeing it.
In the end I just went bare metal with OPN for simplicity, created the VLAN interface and named it VLAN0.911 and put it on WAN hung off the physical igc interface which had the cloned MAC of the HX220, rebooted to get nothing… after a bit of head scratching and eventually rebooting the ONT (shouldn’t be needed with the cloned MAC, but I was running out of options), it worked.
Unfortunately in my case I am missing some speed as my 1.2/1 profile seems capped at 1/1 for some reason, i’ve verified the LAN to WAN connection is producing a real world 2.37Gb/s, so Yayzi are investigating if it’s a profile issue, as i’m on the newest Nokia XGPON rather than the older Calix units, hopefully this week