Hi Viresh,
There has been a behaviour change in SQLA 17 in how the host names in the server certificate are verified in the client. Maybe you have hit this change.
In SQLA 17, the host name of the client must match one of the host names on the server certificate. The client should use one or more of the protocol options: certificate_name, certificate_company, or certificate_unit to verify the host name in the server's certificate or, if it doesn't care, set skip_certificate_name_check=on. These go in the network protocol if you are using UltraLite, eg ULSyncParms.StreamParms="skip_certificate_name_check=on;other_options"
Hope that helps.