Help cant fix rss feed so that it can be used in mailchimp again

For some reason the rss feed to campaign stopped parsing the feed and after contacting Mailchimp support they indicated me that the current feed is not valid according to this:

https://validator.w3.org/feed/check.cgi?url=otzerling.com%2Ffeed%2Ffeedname

Is important because through the rss, events are sent automatically to the subscribed mailing list. The error is: connecting to feed failed.