cant get feed to download on channel

That's an extremely vague description on your problem. You won't get much help without providing more details:

I have a properly formatted JSON feed

How about posting your JSON feed, or a stripped down test feed that manifests the same problem.

set up

Where is the feed "set up" - has the channel been published, or do you have a feed that currently only exists on your server that you're trying to publish?

but my server is giving me

Where and when exactly is your server giving you an error - are you seeing this in your server logs, in the Roku Direct Publisher console, when you attempt to run the channel, etc?

a 406 Not Acceptable error

In general, such an error indicates that your server has received a request specifying a value for Accept, Accept-Charset, Accept-Encoding, Accept-Language, Accept-Ranges, etc. that your server cannot handle.

when your server pings for the data.

Again, when does this take place, when you attempt to run the channel on your Roku device?

As such my feed won't load the video into my channel.

What specifically happens when you say the feed "won't load the video into my channel"?

I can't find any proper documentation on what is going on.

The Direct Publisher documentation, or at least feed specifications, are documented in https://github.com/rokudev/feed-specifications/blob/master/mrss-feed-specification.md

Help please. My assumption is that my server is not communicating with the ROKU server properly causing the issue.

If you think you have a problem involving your server then you should examine the traffic to and from your server. Posting the server requests and responses may give some clue as to why your server is returning a 406 error.

Ok, let me add more info. the JSON I am using is the same JSON as https://api.myjson.com/bins/4tu28
I have it set up as a php page. Added headers in place to try and solve the problem as seen below.

<?php
    header('Content-Type: application/json');
    header('Access-Control-Allow-Credentials: true');
    header('Access-Control-Allow-Orgin: *');
?>
the feed is sitting on my server, http://api.herbadvisors.com/channeltest.php

When i add the URL to my roku Channel via the developer portal it finds the link fine. however it will never get past a download status of

Unable to download from feedUrl.

But I get no further error. If i connect to the feed at https://api.myjson.com/bins/4tu28 it loads the feed fine with no issue. JSON content is the same.

 I am seeing the 406 Not Acceptable error on my server logs corresponding to the attempts to download the content by the roku channel.

 I have not been able to get to the point of publishing as it never gives a green light status for the feed.

In my logs I am seeing this
52.200.168.210 - - [07/Jan/2017:21:08:06 -0600] "GET /channeltest.php HTTP/1.1" 406 226 "-" "Mozilla/5.0"

It looks to me like a server configuration issue. I would get rid of the PHP headers, just leaving the raw feed in a file by itself. Then look for a way to configure the server to send JSON content. I'm not familiar with nginx, but I'd assume there's a way you could give your feed file an extension like ".json" and specify in a server config file (./conf/mime.types.default) a MIME type association for .json files of "application/json".

This one is tricky... 
The solution? Go buy a Godaddy hosting account (don't use Bluehost, or Hostmonster)... Save your information as a .json file, upload that to your new location on your newly purchased hosting server, then YES. 4 hours later, that's the answer. 

Your feed works for me on my test channel.

I got 10 items ingested.

Do you have your categories set to define from feed?