Missing page from 2 positions of Yandex search?

Question

Search Engine Optimization

Hello, I have optimized the main page of the site for the request "School of Rhythmic Gymnastics of St. Petersburg". For several months, she was in 2-4 positions, and on the first page for related queries. Now I can't find it at all.
This School has 8 branches in St. Petersburg, a month ago I made a page for each and linked to each other and displayed links at the bottom of the main page, they are now in the top for queries in their district of the city. Maybe because of this? How then to be? How to return the main page to the top and leave the pages of affiliates in their current places?

Answer 1

I don't have a simulation problem.
Great to see you on the first page for your desired query.
True, I see not the main, but the internal page, but the point is that it is simply more relevant to the request.
In general, this is more like trying to get an additional external link.)

Answer 2

One of the reasons Yandex has recently been updating its search database frequently, and therefore the site may change positions from time to time.