Hi
Your test shows a 403 - Access forbidden error, so that's not coming from robots.txt (which does not block access in any way).
This is not from 4SEO either, which have no way of blocking based on the visitor user agent.
It could be from 4SEO if YOU added a blocking rule (under SEO Tools | SEO Rules) and deliberately blocked Yandex robots IP addresses.
I assume you did not do that, so possible options are:
- something in your .htaccess file
- a "security" extension installed on your site, maybe blocking visits from Russia (where Yandex is)
- a firewall by your hosting company
Best regards
Yannick Gaultier
weeblr.com / @weeblr