Hi,
I am not an Snapcenter guy, but trying to give some direction if it may be useful.
I see that you mentioned - 'I have install this plugin on port 8146' ? I think 8146 is the Server Port, could you ensure the Plugin is listening on port 8145.
Linux/centos = Plugin service port : "8145".
Windows = Snapcenter Server Port : "8146"
This is from KB:1071192, don't know if this is valid, but you can try.
Validate communications from the SnapCenter server to the plug-in on port 8145 by using the following url on the SnapCenter server:
https://<hostname>:8145/ConfigureService/reloadConfigs
If the url fails to connect, check for firewalls that may be blocking communication to port 8145 . Also check to see if there is another process using port 8145 on the plugin host.