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Accessing The Cancer Imaging Archive's Download Manager directly through a proxy server is currently not supported. If your only access to the Internet is through a proxy server, then our current recommendation is to ask your IT Department to allow your workstation to bypass the proxy server for direct access to https://public.cancerimagingarchive.org
Java may be configured to utilize proxy settings; however, the developers of NBIA have not tested whether Download Manager correctly handles such settings.