The relevant error in the log is:
:debug:destroot Executing proc-post-org.macports.destroot-destroot-0
:debug:destroot Fetching images:
:debug:destroot /opt/local/bin/python2.7 /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_science_uhd/uhd/work/destroot/opt/local/share/uhd/utils/uhd_images_downloader.py --install-location=/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_science_uhd/uhd/work/destroot/opt/local/share/uhd/images
:info:destroot Images destination: /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_science_uhd/uhd/work/destroot/opt/local/share/uhd/images
:info:destroot Downloading images from: http://files.ettus.com/binaries/images/uhd-images_003.008.004-release.zip
:info:destroot Downloading images to: /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_science_uhd/uhd/work/.tmp/tmp1Te9G5/uhd-images_003.008.004-release.zip
:info:destroot Downloader raised an unhandled exception: [Errno 54] Connection reset by peer
:info:destroot You can run this again with the '--verbose' flag to see more information
:info:destroot If the problem persists, please email the output to: support@ettus.com
Ports should not attempt to download files, other than in the fetch phase.