According to the documenation, BigBreaks is the way to go otherwise it breaks at the first character. \def\UrlBigBreaks{\do/\do-\do:} See
\def\UrlBigBreaks{\do\/\do-\do:} See: http://texdoc.net/texmf-dist/doc/latex/url/url.pdf I had the problem that a line break was inserted always after http:http:, even when using \UrlBreaks\UrlBreaks, the documentation clarified that this is the intended behavior.