for some security reason i only allow to use TLS_AES_256_GCM_SHA384 and TLS_ECDHE_ECDSA_with_AES_256_GCM_SHA384 , so i disabled all weak Ciphersuite but when I disable TLS_RSA_WITH_AES_256_GCM_SHA384
my website gets " Unable to connect " and even my startup method doesn't call
information :
Asp.Net 4.8
AspNet.Mvc version 5.2.7
Debug environment= on Windows 10 , server = Windows Server 2019
TLS_ECDHE_ECDSA_with_AES_256_GCM_SHA384 requires you to use a so-called "ECC certificate" (whose signature algorithm should be ECDSA). That often is not the case, and yours hit the same.
Either you switch to such a certificate in site binding, or you re-enable TLS_AES_256_GCM_SHA384.