It sounds like you're retrieving the media from a web source in IBM Installation Manager and that is failing to download for some reason. I haven't seen this in particular, but you may be better off downloading the media from Passport Advantage & FixCentral (ibm.com/support/fixcentral) manually and going through the WebSphere install that way.
You might be able to get more information from the Installation Manager logs to understand the failure better. Open the File menu in Installation Manager and choose "View Logs". Find the log entry that corresponds to your attempt. Normally this would get written to C:\ProgramData\IBM\Installation Manager\logs on a Windows environment. Review the output of that to see if that gives you more information (such as access is denied error or connection timeout).
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Steven Shull
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