To update public repo urls for HDF and HDF utils, please update the repoinfo.xml below on the ambari server host and restart ambari-server service using command [0], let me know if this works for you.
/var/lib/ambari-server/resources/mpacks/hdf-ambari-mpack-3.4.1.1-4/stacks/HDF/3.3/repos/repoinfo.xml
/var/lib/ambari-server/resources/mpacks/hdf-ambari-mpack-3.4.1.1-4/stacks/HDF/2.0/repos/repoinfo.xml
/var/lib/ambari-server/resources/mpacks/hdf-ambari-mpack-3.4.1.1-4/stacks/HDF/3.2/repos/repoinfo.xml
/var/lib/ambari-server/resources/mpacks/hdf-ambari-mpack-3.4.1.1-4/stacks/HDF/3.0/repos/repoinfo.xml
/var/lib/ambari-server/resources/mpacks/hdf-ambari-mpack-3.4.1.1-4/stacks/HDF/2.1/repos/repoinfo.xml
/var/lib/ambari-server/resources/mpacks/hdf-ambari-mpack-3.4.1.1-4/stacks/HDF/3.4/repos/repoinfo.xml
/var/lib/ambari-server/resources/mpacks/hdf-ambari-mpack-3.4.1.1-4/stacks/HDF/3.1/repos/repoinfo.xml
[0]
#ambari-server restart