Messed around for hours tonight with my router's port forwarding settings and DMZ and all that stuff related to the NAT...
Still couldn't get it open any more than Moderate, so hopefully that won't mess things up at all for the group.
Last year I managed to get it to Open, but that was before both my modem and router had meltdowns. Could not for the life of me replicate whatever I managed to do before to make that happen.