Arvixe is the web host. I have had the site set up with no plugins except Powerpress to test it. I am currently adding some plugins back – right now just some very basic ones (broken link checker, etc.)
I find that about half the time when I enter my feed into W3c, I get this:
It looks like this is a web page, not a feed. I looked for a feed associated with this page, but couldn’t find one. Please enter the address of your feed to validate.
Source: https://twoormoretotango.com/?feed=podcast
<html>
<head>
<title>Visitor anti-robot validation</title>
<meta charset="UTF-8" />
<meta http-equiv="Content-Type" content="text/html;charset=UTF-8" />
<link rel="stylesheet" type="text/css" href="css/style.css" />
</head>
<body>
<div class="container">
<div>
<h1>Dear visitor</h1>
<p>To reach the website securely, please fill in the characters shown below.</p>
<p><strong></strong></p>
</div>
<div class="left">
<img src="img/logo.png" alt="" />
</div>
<div class="right">
<form method="post" action="/verify.php">
<script type="text/javascript" src="https://www.google.com/recaptcha/api/challenge?k=6LfRteUSAAAAAFQ4IlQQdjP_E7ek9ElCzSo5TDxC"></script>
<noscript>
<iframe src="https://www.google.com/recaptcha/api/noscript?k=6LfRteUSAAAAAFQ4IlQQdjP_E7ek9ElCzSo5TDxC" height="300" width="500" frameborder="0"></iframe>
<textarea name="recaptcha_challenge_field" rows="3" cols="40"></textarea>
<input type="hidden" name="recaptcha_response_field" value="manual_challenge"/>
</noscript>
<input type="hidden" name="origin_url" value="" />
<input type="submit" value="Delist" />
</form>
</div>
<div class="clear"></div>
<div>
<h1>Why is it necessary?</h1>
<p>Your IP address (128.30.52.88) has been blocked for security reason. Probably your IP address has been used for violation of server security rules before.</p>
<p>We have to make sure that this is not a malicious visit by an automated robot. Filling in the captcha is required to delist you IP address.</p>
<p>Thank you.</p>
<hr/>
128.30.52.88 comes back to MIT, and I saw posts online saying it should be whitelisted because w3c uses it. Not sure why I get that so often when I enter my feed in. Seems random – part of the time I get that, part of the time valid. All other validators other than feedvalidator.org come back valid.