There is an ongoing outage on the primary CPAN mirror. It is possible to work around the issue by using MetaCPAN as a mirror.

$self->serializer->register_ns("http://schemas.xmlsoap.org/wsdl/soap/","soap");
$self->serializer->register_ns("http://schemas.xmlsoap.org/wsdl/","wsdl");
$self->serializer->register_ns("http://schemas.xmlsoap.org/soap/http","http");
$self->serializer->register_ns("http://www.w3.org/2001/XMLSchema","xsd");