Unbound fails to start if it binds to down/nocarrier interface
How to reproduce:
1) Select OPT1 for example, in "Network Interfaces" list;
2) Disable OPT1 interface;
3) Reboot firewall (or receive new WAN ip);
Nov 20 15:22:43 pf41 php-fpm: /system_routes.php: The command '/usr/local/sbin/unbound -c /var/unbound/unbound.conf' returned exit code '1', the output was ' unbound[18329:0] error: can't bind socket: Can't assign requested address for 172.16.0.1 port 53  unbound[18329:0] fatal error: could not open ports'
Services / DNS Resolver -> save + apply