Hello and welcome! 
I don’t know the exact limit, but 1 629 items are probably way too many. 
So you will either have to cap the number of posts in your feed or try your luck authoring and providing a JSON Feed instead.
Hello and welcome!
I don’t know the exact limit, but 1 629 items are probably way too many.
So you will either have to cap the number of posts in your feed or try your luck authoring and providing a JSON Feed instead.