By default, RayVentory Portal uses TLS 1.0 to upload and receive files over HTTPS. This can lead to problems if the server / client RayVentory Portal is communicating with only has TLS 1.2 enabled for security reasons.
The following registry values will force .NET and therefore also RayVentory Portal to use TLS 1.2:
Name: SystemDefaultTlsVersions Type: DWORD Data: 1
Name: SchUseStrongCrypto Type: DWORD Data: 1
For the changes to take effect, the machine needs to be rebooted.