If that doesn’t help, please share the URL of the feed/podcast here on the forum, so we can test it.
Edit: I see that you had tried to upload an image. I just edited your post so that the image is visible.
404 means that the podcast feed is offline -it doesn’t exist (anymore). Most likely the podcast was taken down. Or they changed website address and didn’t do it the proper way. Either way, you should probably contact the podcasters to ask what happened.