There seems to be a bug on Yandex.Store. Today Yandex.Store stopped working, again. I'm either getting error message: connection error or server unavailable.

After some testing it seems that at first time you can use Yandex.Store over mobile data connection but after some time it stops working over mobile data connection. To recover you have to use it over WLAN and after that it also works over mobile data connection. Until it breaks again?

There is settings about WLAN and mobile data connections on Yandex.Store but at least when it is in that error state those settings don't do anything/help you out of it.