You may need also to bind ssl certificate to the specific port number using netsh or HttpConfig tool depending from OS version. Detailed instructions can be found here
In your case it could be:
netsh http add sslcert ipport=0.0.0.0:18732 certhash=<certhash> appid={<guid>} clientcertnegotiation=enable
where
certhash = your certificate Thumbprint(X509Certificate2.Thumbprint)
appid = could be just Guid.NewId()