FreeSpeech

You cant and wouldn’t want to use both W3 Total Cache and WP SuperCache as they do very much the same thing, I have found WP SuperCache the far more reliable, a much easier setup.

You’re right, i didn’t use it, when i ftp’d i saw the plugin name, i disabled by renaming, I was expecting something silly in the .htaccess, but this was the cause. So while I didn’t use it, i did see the effect of it.

Maybe it would be good to set “No Redirect” as default with a warning that using it will damage your SEO. if you do already, great.

client saw this as fixing legitimate 404 errors that need to be addressed by replacing missing files, he has a lot of 404 errors reported by google from a previous malware infection.
It’s good that Google sees /buyviagrahere as a 404 and not some how related to his homepage which is what using this plugin implies, this plugin is SEO assisted suicide, I chose my words carefully.
If you google “404 to 301 seo” you will see I am not alone in thinking this plugin really should not exist, you’re obviously a skilled dev, it’s the concept thats wrong here.

Still not connecting on debug,
but the subscribers are now getting updates on comments (did you change something?),
And yes, the there is an nginx proxy with the SSL (forced), but apache at the back is port 80 only, but then again in WP settings, it’s https. That might be a bit odd, all other site with the same proxy setup have ssl both back and front end, none having the same issue.
But as I said initially, the 400 error is expected on a get to that xmlrpc url. whys it not doing a post?