Ставьте лайк если вы тоже не знали, что Prosody was unable to find lua-unbound
This package can be obtained in the following ways:

Debian/Ubuntu | sudo apt install lua-unbound
luarocks | luarocks install luaunbound
Source | https://www.zash.se/luaunbound.html

Old DNS resolver library will be used
More help can be found on our website, at https://prosody.im/doc/depends