opnsense-revert -r 20.7.6 unbound
root@opnsense:~ # opnsense-revert -r 20.7.6 unboundFetching unbound.txz: ............................... failed
curl -o unbound.txz http://mirror.sfo12.us.leaseweb.net/opnsense/FreeBSD%3A12%3Aamd64/20.7/MINT/20.7.6/OpenSSL/Latest/unbound.txz
Please check the interfaces it is listening to. Maybe there is something wrong. Change this setting and hit save. Then change it back and save again.