Make sure you're contacting hhs.gov and not www.hhs.gov, the www. subdomain reacts differently.

  $ printf 'GET / HTTP/1.1\r\nHost: hhs.gov\r\n\r\n' | nc hhs.gov 80
  HTTP/1.1 302 Found
  Date: Mon, 14 Oct 2024 01:38:29 GMT
  Server: Apache
  Location: http://www.hhs.gov/web/508//
  Content-Length: 212
  Content-Type: text/html; charset=iso-8859-1
  
  <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
  <html><head>
  <title>302 Found</title>
  </head><body>
  <h1>Found</h1>
  <p>The document has moved <a href="http://www.hhs.gov/web/508//">here</a>.</p>
  </body></html>
  ^C
  $ printf 'GET / HTTP/1.1\nHost: hhs.gov\n\n' | nc hhs.gov 80
  HTTP/1.1 400 Bad Request
  Date: Mon, 14 Oct 2024 01:38:40 GMT
  Server: Apache
  Content-Length: 226
  Connection: close
  Content-Type: text/html; charset=iso-8859-1
  
  <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
  <html><head>
  <title>400 Bad Request</title>
  </head><body>
  <h1>Bad Request</h1>
  <p>Your browser sent a request that this server could not understand.<br />
  </p>
  </body></html>

Ahh, that was it, thanks.

And this whole exercise is an example of why this is a non-starter proposal (at least the "change existing implementations" part).

How much do we expect the domain owners to invest in changing an implementation that already works? Hint: it's a number smaller than epsilon.

Google might, but their volume is so high they care about the cost of individual bytes on the wire.

This exercise was about demonstrating that our security can't rely on making sure there's a carriage return in HTTP line termination, because there is no such norm. See the root of the thread, where I asked the question.

Oh, I agree it's about that too, but my point is you've already volunteered more time and resources investigating the situation than most companies would be willing to spend.