imap not working on pdd.yandex.ru

Question

Yandex

A day after registration, it stops connecting to imap on Yandex mail for the domain (pdd.yandex.ru).

Everything works on pop3 and through the site, so the problem is not in the passwords.
All old accounts registered more than six months ago through imap work, so the problem is not in the network.

If you delete the box, create a new one with the same name, then it connects during the day, and the next day it stops, and I checked it on several domains.

Debian system, thunderbird client, internet search doesn't help.

In general, the question is what to watch, where to dig?

Answer 1

Yesterday users of Windows Outlook imap began to fall off. Transplanted while on the web muzzle.

Answer 2

after 9 p.m. until 6 p.m. Moscow time, IMAP is stably turned off - either it says an error, or that the server is not responding. On the web, all the checkboxes are in place.
Looks like squeezing users into the web.
I will suffer until Friday, and I will withdraw domains from Yandex.