IPFW works just fine in 15.0. Doing the Windows-ism and just nuking the whole thing is not going to bring you any insights here. If you reboot with IPFW competely disabled, you can at least eliminate IPFW as a possible cause. If that doesn't make any difference, look at your unbound configuration. I looked into Unbound itself for a little bit, and there's some stuff going on with certificates and the like for the control interface. If you're not going to remote-control your unbound instance, you could just disable unbound-control altogether and be done with that. I'd also be interested in seeing whether unbound really isn't listening anywhere. What does sockstat -4 tell you, and is there any logging for unbound in /var/log?