If there is no HTTPS proxy in play, maybe it is an SSL certificate issue. Print the complete response headers to maybe find out more. Also switch IO::Socket::SSL debugging on:

$IO::Socket::SSL::DEBUG = 3;
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If you've determined that IO::Socket::SSL doesn't want to talk to the remote side, see p5-ssl-tools, which contain tools that will give you more diagnostics as to what part of the SSL connection fails.