Hi,
Hope you are doing good.
Sriram is right as usual, SAP KBA 1727745 - RFC connection error while executing transaction RZ70
usually helps in such cases. Also review what is the security level enabled in the instance as per the configuration of parameter gw/reg_no_conn_info. This parameter will enable special settings that should be controlled in the configuration of reginfo file. Further information about this parameter is also available in the following link:
____________
Kind Regards,
Hemanth
SAP AGS