Why can't Kindle 5 access certain websites (more in the table of contents)?

Question

Books

When trying to access getpocket.com, twitter.com, vk.com, and some other sites using Kindle 5, the browser began to issue "The web browser cannot establish a secure connection to this site."
What are the ways to solve the problem?
Kindle 5, firmware 4.1.1 (1813030025), Russification is required. There are ads on the reader.

Answer 1

I heard that sometimes HTTPS fails if the time is set incorrectly.

Answer 2

For a long time I also could not understand what the problem was, today I was surfing the Internet through the Kindle browser, but after 20 minutes a window suddenly popped up that kindle was being updated. Within a minute, it automatically updated and rebooted. After that, all vkontakte, twitter and facebook earned.