Tensorflow serving grpc client error 12

I am currently trying to serve a simple model via tensorflow serving and then I want to call into it via gRRC using node.js. I felt the easiest way to learn/understand this would be to break it down to the simplest model possible. Please forgive the naming as I originally started doing this with a Mnist tutorial but I wasn't successful there either. So the name still says mnist, but it is just a simple calculation implementation.

I created and exported the model with the below code: -- Simple Model --

x = tf.placeholder(tf.float32, shape=(None))
y = tf.placeholder(tf.float32, shape=(None))
three = tf.Variable(3, dtype=tf.float32)
z = tf.scalar_mul(three, x) + y

-- Export --

model_version = 1
path = os.path.join("mnist_test", str(model_version))
builder = tf.python.saved_model.builder.SavedModelBuilder(path)
with tf.Session() as sess:
    sess.run(tf.global_variables_initializer())

    builder.add_meta_graph_and_variables(
    sess,
    [tf.python.saved_model.tag_constants.SERVING],
    signature_def_map = {
        "test_mnist_model": tf.saved_model.signature_def_utils.predict_signature_def(
            inputs={"xval": x, "yval":y},
            outputs={"spam":z})
    })
    builder.save()

The message in the end when I ran this seems to be successful:

INFO:tensorflow:No assets to save. INFO:tensorflow:No assets to write. INFO:tensorflow:SavedModel written to: b'mnist_test/3/saved_model.pb'

So I then run tensorflow server and point it to my model via the below line and the server states it is runnign at 0.0.0.0:9000:

../../bazel-bin/tensorflow_serving/model_servers/tensorflow_model_server --model_base_path=mnist_test --model_name=calctest --port=9000

I then proceeded to setup the .proto file and it contains this:

syntax = "proto3";

option java_multiple_files = true;
option java_package = "io.grpc.examples.mnisttest";
option java_outer_classname = "MnistTestProto";
option objc_class_prefix = "MNT";

package mnisttest;

// The greeting service definition.
service Greeter {
  // Sends a greeting
  rpc test_mnist_model (InputRequest) returns (OutputReply) {}

}

// The request message containing the user's name.
message InputRequest {
  float xval = 1;
  float yval = 2;
}

// The response message containing the greetings
message OutputReply {
  float spam = 1;
}

Finally I setup a mnistclient.js file which I run under node.js and it contains the below code:

var grpc = require('grpc')
var PROTO_PATH = __dirname + '/../../protos/mnisttest.proto';

module.exports = (connection) => {
    var tensorflow_serving = grpc.load(PROTO_PATH).mnisttest;//.serving;
    console.log(tensorflow_serving);

    var client = new tensorflow_serving.Greeter(
        connection, grpc.credentials.createInsecure()
    );

    return { 
        test: () => {
            console.log(client);
            return client.testMnistModel({xval:5.0,yval:6.0}, function(err, response){
                if(err){
                    console.log("Error: ",JSON.stringify(err));
                    return {Err: JSON.stringify(err)};
                }
                console.log('Got message ', response);
            });
        }
    }
};

function main() {
    var cli = module.exports('localhost:9000')
    cli.test();
}

if( require.main === module){
    main();
}

With the Model running on tf server, when I run the client under node.js I get the below error. I am also printing out the info under client, but when I looked up what the error code 12 meant, it stated the following: Operation is not implemented or not supported/enabled in this service

I have been at this for quite some time and I am assuming that there is just some piece of this that I am blatantly missing. Is anyone able to provide any insight as to why I can't get this simple call into the model working?

I have not ever been able to get a TF model served up yet and thought taking this simple approach would work best, however I can't even get this to work. Any help on this would be a great help! Thanks in advance!

{ InputRequest:
   { [Function: Message]
     encode: [Function],
     decode: [Function],
     decodeDelimited: [Function],
     decode64: [Function],
     decodeHex: [Function],
     decodeJSON: [Function] },
  OutputReply:
   { [Function: Message]
     encode: [Function],
     decode: [Function],
     decodeDelimited: [Function],
     decode64: [Function],
     decodeHex: [Function],
     decodeJSON: [Function] },
  Greeter: { [Function: Client] service: { testMnistModel: [Object] } } }
Client { '$channel': Channel {} }
Error:  {"code":12,"metadata":{"_internal_repr":{}}}

via xtr33me