Cannot add feed from tomaselli.page

problem
1

I can access the following feed from my browser:

https://tomaselli.page/blog/feeds/feed.xml

However, when I try to add it to Newsblur, I get the following error message:

This address does not point to an RSS feed or a website with an RSS feed.

I also tried downloading the feed with curl and I got a certificate error. They use LetsEncrypt; perhaps this is an SSL-related issue?

2

https://validator.w3.org/feed/check.cgi?url=https%3A%2F%2Ftomaselli.page%2Fblog%2Ffeeds%2Ffeed.xml

does not validate. it isn’t even seeing it as a feed with some problems: the validator does not see a feed.