Error: Feed type not recognized (different from #20) 

https://feeds.pinboard.in/rss/t:hardware

AFAICT its a valid feed (https://validator.w3.org/feed/check.cgi?url=https%3A%2F%2Ffeeds.pinboard.in%2Frss%2Ft%3Ahardware),

and the underlying site is in fact giving me a usable status (200).