Synchronization editor Remote connection - The underlying connection was closed: An unexpected error occurred on a send.

Hi All,

we are setting up Lotus Domino synchronization project. We have one Job server for all connectors, so this server is "Gateway server". Tools are on another server, so we want to use remote connection to configure synchronization.

We have configured the RemoteConnectionPlugin, but when we start the configuration wizard and we select remote server, we get the following error - error is not related to Domino only, for the test we tried to set up the AD through the remote connection and the error was the same: "An error occurred while sending the request. System.Net.Http.HttpRequestException: An error occurred while sending the request. --->

System.Net.WebException: The underlying connection was closed: An unexpected error occurred on a send. --->
System.IO.IOException: Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host. --->
System.Net.Sockets.SocketException: An existing connection was forcibly closed by the remote host".
Both servers are in the same network and there is no firewall in between. For the test purpose there is default "Domain User" group set in the RemoteConnectionPlugin. Port is set to the default - 2880. 
I have copied tools to the job server and I was able to configure the synchronization, so it works, but we want to remove the tools and we want to be able to modify the settings from the remote server. 
OneIM version: 9.1.