Hi Alberto,
It helps that you give the URL of the site you are connecting to, because the problem is on their side, not your side.
Using the URL I was able to duplicate in NetDemo and also determine the appropriate fix.
The site is pretty insecure. You can see this by going to
https://www.ssllabs.com/ssltest/analyze.html?d=www.siogranos.com.arAs you can see there are all kinds of things wrong - the primary ones being only support for TLS 1.0 and the (very) limited number of weak, and insecure ciphers being supported.
To connect to a site like this you seen to set the ciper list to AES128-SHA and turn off the remote certificate ca root check.
(The site is using a certificate which we don't "trust".)
ThisWebClient.SSLCertificateOptions.CiphersAllowed = 'AES128-SHA'
ThisWebClient.SSLCertificateOptions.DontVerifyRemoteCertificateWithCARoot = true
all the other settings can be left to default values.
Of course the above code will break when they do finally get around to securing the server, and then the AES cipher will no longer work.
Cheers
Bruce