Error in logs and Sonarr unresponsive

I have been seeing the following in my Sonarr logs lately, with Sonarr eventually bombing out.
I run Sonarr as a Freenas plugin.

System.Net.WebException: Error: ConnectFailure (Connection refused) —> System.Net.Sockets.SocketException: Connection refused
at System.Net.Sockets.Socket.Connect (System.Net.EndPoint remoteEP) [0x00000] in :0
at System.Net.WebConnection.Connect (System.Net.HttpWebRequest request) [0x00000] in :0
— End of inner exception stack trace —
at System.Net.HttpWebRequest.EndGetRequestStream (IAsyncResult asyncResult) [0x00000] in :0
at System.Net.HttpWebRequest.GetRequestStream () [0x00000] in :0
at RestSharp.Http.WriteRequestBody (System.Net.HttpWebRequest webRequest) [0x00000] in :0
at RestSharp.Http.PostPutInternal (System.String method) [0x00000] in :0
at RestSharp.Http.AsPost (System.String httpMethod) [0x00000] in :0
at RestSharp.RestClient.DoExecuteAsPost (IHttp http, System.String method) [0x00000] in :0
at RestSharp.RestClient.Execute (IRestRequest request, System.String httpMethod, System.Func`3 getResponse) [0x00000] in :0

Not sure what it means or if i should be concerned

It means Sonarr can’t connect to whatever its trying to connect to (indexer, download client, etc), but wouldn’t lead to Sonarr crashing.

Trace logs of the crash would be the first thing to look at.