> IIRC there was something with the current network drivers preventing it

Yes, Multicast support according to geit:

https://morph.zone/modules/newbb_plus/viewtopic.php?forum=32&topic_id=9037&start=11

Relatively easy to add according to Nadir:

https://morph.zone/modules/newbb_plus/viewtopic.php?forum=32&topic_id=9037&start=21