Restarting org.apache.sling.scripting.sightly  bundle resolved the issue.. not sure what caused it

Apart from what @praveenjain  already mentioned, also see if you are not trying to access any page or sitemap page from dispatcher url as in that case you might be accessing already cached page in dispatcher. If that is the case, clearing dispatcher cache should resolve the issue.

As you mentioned , remaining pages are replicating successfully.Can you verify :Is there anything different in /content/pagepath with respect to other pages, delaying activation and causing timeout ?Also check this out : https://helpx.adobe.com/experience-manager/kb/SocketConnectionTimeout.html

In case  of author AEM 6.5 instance, it can be done by excluding the servlet path in “Apache Sling Authentication Service"https://queryresolved.com/2020/06/03/aem-6-5-author-exclude-a-url-from-authentication-requirement/