Discovered, not indexed

Good afternoon! Recently I wrote a series of articles, but even when manually sent for indexing, each of them does not get into it in any way, they only appear in the report "Found, not indexed", you can tell what the matter is, here are examples of pages.

I also noticed that on July 19 I had problems with the caching plugin, after the update, as a result, this increased the response time in the console report from 250 to 650, and on the hosting I saw the load not 2-3%, but 30-40%. Apparently, the bot did not like this, and he decided not to strain the site. I have fixed this error and see that the response time is back to 250 milliseconds, as it was before the indexing issues. At the moment, I already have 12 new articles that cannot get into the index, although I see the sitemap, it is being updated in the office. Who will tell you how to explain to the bot that the load is now normal and force it to index the content?

I had an error still Missing nameservers reported by parent, but I fixed it.Examples of pages, I periodically try to send them for indexing manually via the console, but so far there is no result. it feels like they are in a queue, but the bot has not yet reached them and it is not clear when it will come.

http://pyatilistnik.org/dell-r740-server-testing/

http://pyatilistnik.org/how-to-turn-your-photos-into-a-beautiful-movie/

http://pyatilistnik.org/jcp024-lifecycle-controller-in-use/

http://pyatilistnik.org/how-to-install-the-operating-system-on-the-dell-r740/

http://pyatilistnik.org/error-rac0509-the-server-temporalily-unavailable/