Go gRPC API with loraserver-docker: tls: oversized record received


I’m trying to use the gRPC go client without certificates but when I try any API call I have this error:
{"level":"error","message":"rpc error: code = Unavailable desc = all SubConns are in TransientFailure, latest connection error: connection error: desc = \"transport: authentication handshake failed: tls: oversized record received with length 20527\"","ts":"2018-11-13T14:02:38.694208Z"}

My go code look like this:

conn, err := grpc.Dial(url,
	grpc.WithTransportCredentials(credentials.NewClientTLSFromCert(nil, "")),
		token: "verysecret",

and this:

ctx, cancel := context.WithTimeout(context.Background(), time.Second)
defer cancel()

createResp, err := as.loraAppClient.List(ctx, &apilora.ListApplicationRequest{
	Limit:          10,
	Offset:         0,
	OrganizationId: "loraserver",

I tried to set certificates but still having same error… Do you have any idea?