NTLM is not supported by soap4r in any way, while httpclient supports it.
If enabling auth is not an option, you might consider using kerberos, i.e. negotiate auth method. Including this in sharepoint is a bit complicated, but it basically boils down to doing the following on the command line server:
cscript adsutil.vbs set w3svc/1/NTAuthenticationProviders "Negotiate,NTLM"
Perhaps he has some strange enslavements, check out this forum post for more information . Finally, you need to set authentication in soap4r using auth = instead of basic_auth = I think.
Arthur
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