Failed to fetch schema. Please check your connection sitecore xp graphql configuration

I configured the graphql in sitecore cms XP, but when launching graphql ui with query giving me the error,

“error”: “Failed to fetch schema. Please check your connection”

I am trying to run the simple graphql query, it is giving me issue.

I am running the sitecore xp version 10.3.1
-installed the jss headless package installed “Sitecore Headless Rendering 21.0.1”
-enable false in authencation and true in require apikey in file sitecore.service.graphql.config
-update path “/sitecore/api/graph/items/” in sitecore.own.authencation.config
-remove example from the “Sitecore.Services.GraphQL.Content.Master.config” file
-created api key in sitecore