Seems like the session isn't persisting across subdomains, which is why logging in on .site.ru redirects to site.ru without maintaining authentication. Here are a few things you can check:
* Cross-Subdomain Cookies – Ensure cookies are set for …
The issue has been resolved! The problem was due to outdated values in Oneall Social Networks > VKontakte > Setup, specifically in the Website address and Base domain fields. I updated them according to Oneall’s latest instructions, and everyt…