Why does tlstest.paypal.com work from browser but not from my PHP code (useful for Paypal IPN)?

Question

After 2018 June 30th, Paypal won\'t accept non-TLS 1.2 + HTTP 1.1 requests anymore.
They created the URL https://tlstest.paypal.com/ to test if connections are OK. If we

Answer 1

For completeness, here is a working code (full credit to PatrickMevzek's answer):

Here is the answer from server:

# php -f test.php
HTTP/1.1 200 OK
Content-Type: text/html
Content-Length: 20
Date: Fri, 22 Jun 2018 20:19:56 GMT
Connection: keep-alive

PayPal_Connection_OK