that the 404 file...
server.error-handler-404
That's probably means the /bandwidth is checked in the document-root. My guess is that your alias isn't working ...
Do you have the alias module loading in your lighttpd ? Look at the server.modules in your /etc/lighttpd/lighttpd.conf
Don't forget that the conf file could be overwrited by pi-hole update/reinstall, etc...