520 error on rss feed

Hi,

A third-party tool is trying to access an rss feed on one of our websites but the connection returns a 520 error in the Cloudflare logs. They are able to access feeds on our other sites.

There is nothing wrong with the rss code, it works in all aggregators and no errors are highlighted in the validators. I can also see that anyone else accessing the feed is able to do so and a 200 code is returned. It appears to be just this one visiting site where this an issue.

My understanding is that a 520 error maybe relates to an issue on the hosting server rather than at the Cloudflare end? Could it be the IP address is being blocked for some reason?

Thanks