Error: A requested configuration was not found.

Possible cause: Endpoint Name defined in the Endpoint is incorrect.

Error: BadTcpInternalError:
Error establishing a connection.

Possible cause 1: The server is not running.

Possible cause 2: The port number defined in the Endpoint is incorrect.

Error: No such host is known.

Possible cause: The computer name, IP address or domain name defined in the Endpoint is incorrect.

Error: BadTcpEndpointUrlInvalid:
The Server does not recognize
the QueryString specified.

Possible cause: The protocol defined in the Endpoint is incorrect or mistyped.

Error: No such host is known.

Possible cause: The IP address (or computer name or domain name) defined in the Endpoint is incorrect. This error can also occur if you are using an IP address in the Discovery Domain field to return the list of Endpoint URLs from the server. The endpoints returned by the server will include the server's computer name rather than the IP address, so you need to edit the endpoint URL to replace the computer name with the IP address like this:

opc.tcp://192.168.3.151:51310/OCS4DDataLink/DataAccess

The Endpoint URL is made up of these parts:

protocol://computer name:port number/endpoint name

Error: BadSecurityChecksFailed:
An error occurred while verifying security.

Configuration: Protocol = opc.tcp, Security Policy = Basic128Rsa15 or Basic256, Token Type = any.

Possible cause: This means your connection succeeded but the certificate being used to enable encryption has been rejected by the server. The UA Server needs to accept this certificate in order for this connection to succeed.

Error: An unsecured or incorrectly secured
fault was received from the other party.
See the inner FaultException for the
fault code and detail.

Configuration: Protocol = http, Security Policy = Basic128Rsa15 or Basic256, Token Type = any.

Possible cause: This means your connection succeeded but the certificate being used to enable encryption has been rejected by the server. The UA Server needs to accept this certificate in order for this connection to succeed.

Error: 'CN=Cogent DataHub Data Access Server,
DC=WIN10VM' is not a trusted user certificate.

Configuration: Protocol = any, Security Policy = any, Token Type = certificate.

Possible cause: This means your connection succeeded but the certificate being used to authenticate has been rejected by the server. The UA Server needs to accept this certificate in order for this connection to succeed.

Error: BadIdentityTokenRejected: 
The user identity token is valid but the server 
has rejected it. Possible cause, the user token 
is not supported on the server or my certificate 
is not trusted on the server.

Configuration: Protocol = any, Security Policy = any, Token Type = certificate.

Possible cause: This means that you have successfully connected to the server and your certificate has been passed to the server for authentication. However, the server does not accept your certificate, or does not find it in its trusted store. You need to ensure that the server accepts your certificate, or load it into the trusted store. Then try your connection again.

Error: BadUserAccessDenied:
User does not have permission to
perform the requested operation.

Configuration: Protocol = any, Security Policy = any, Token Type = User Name

Possible cause: This means the user name or password used to authenticate is incorrect.

Error: There was no endpoint listening at
http://win8vm:51311/OCS4DDataLink/DataAccess/discovery
that could accept the message.
This is often caused by an incorrect address or SOAP action.
See InnerException, if present, for more details.

Configuration: Protocol = any, Security Policy = any, Token Type = any.

Possible cause: This may be caused by a firewall between the client and the server not allowing access through the specific port used by the protocol you have chosen. Add new firewall rules as needed to allow access.

Error: The underlying connection was closed:
A connection that was expected to be kept alive
was closed by the server.

Configuration: Protocol = any, Security Policy = any, Token Type = any.

Possible cause: This may be caused by a firewall between the client and the server not allowing access through the specific port used by the protocol you have chosen. Add new firewall rules as needed to allow access.

Error: BadCommunicationError:
A low level communication error occurred.

Configuration: Protocol = any, Security Policy = any, Token Type = any.

Possible cause: This may be caused by a firewall between the client and the server not allowing access through the specific port used by the protocol you have chosen. Add new firewall rules as needed to allow access.

Error: BadInvalidTimestamp: The timestamp is outside
the range allowed by the server.

Cause: The system clock on the client computer is outside the acceptable range defined by the UA server