RSS broken on subdomain yet works on my domains

I upgraded all my sites to 3.1 this week and my domains, of which I have five work fine with RSS. My subdomain https://kidsgenealogy.generationsofstories.net keeps throwing a 404 Error. I have read through the support topics, tried various suggestions and nothing is working. The RSS works on the domain (generationsofstories) but not the subdomain since I upgraded.

Please help!