wp/v2/posts endpoint not working

I’m trying to use the WP Rest API and going to https://www.wels.net/wp-json/wp/v2/posts shows “no route”. We do have the plugin installed, so https://www.wels.net/wp-json/posts DOES work. Is there a conflict going on here? Can you have the plugin installed and still use the built in API as well? We don’t want to lose the old endpoints as we have mobile apps pointed at it.

Thanks.