I have the same problem (C++, R21, Win10).
const maxon::Url url("https://www.mysite.com/myfile.xdl64"_s);
if (url.IoDetect() != maxon::IODETECT::FILE)
returns the ssl certificate error in debug console.
The same code works in R23, R24, R25 (R22 did not check yet).
this is what I got:
sslConnection.DoHandShake failed while connecting to https://www.mysite.com/myfile.xdl64: SSL_do_handshake returned error: SSL_ERROR_SSL (certificate verify failed Certificate Information: not available)
Sorry if this sounds a bit rude but there is no "friendly" way to say it.
This error was a bug on R21, unfortunately, we do not support any more this version and we will not provide any fix for it.