You are trying to read an RSS feed from a site called www.catnat.net which doesn't seem to exist. Try an RSS feed from another site you know works. An example could be the headlines from BBC news.
https://feeds.bbci.co.uk/news/rss.xml?edition=uk
I hope this helps.
Hi Jocelyn,
The error reads "UnknownHostException", which means that the Host or IP could not be resolved.
When I try to visit www.catnat.net, it took the browser quite some time to load the page; I guess the host is not too stable.
You could alert the website owner about this issue, but not much more. For your part, you could build retry mechnisms (if it fails, try again for maximum of 3 trials).
Good luck!