403 Error when proxy enabled

Hello everyone! I’m new to cloudflare and asking for help with configuration,
First of all what i’ve done:
1 - I’ve added new site (let’s say it is sitename.by and its original IP is 100.100.100.100)
2 - I’ve changed two NS records at my registrant to records that cloudflare had gave me
3 - I’ve added A-record and AAAA-record to DNS settings of cloudflare
4 - At the SSL/TLS section I’ve chosen “Full” option and have selected to Always Use HTTPS
5 - At the Firewall section I’ve added a rule “Known Bots” - Allow

Now the problem is that I can reach my site, but if I try to check it with for example YandexBot it gets 403 Error from cloudflare and sees cloudflares IP (lets say it is 99.99.99.99), also in the “Speed” section of cloudflare I see the next message " The Speed test could not run. sitename.by returned a status 403. Try the options below to fix the issue. Review the configuration between your origin server and Cloudflare and ensure that the origin resolves requests successfully Review any existing Firewall Rules applied to your website which may be blocking access to ‘Known Bots’. Contact Customer Support". If i turn off proxy at A-record to “Only DNS” YandexBot gets 200 responce but sees my original IP (100.100.100.100)

Please tell me what else should I configure or check to make it working. Thank you.

Check the Firewall tab for the Events Log to see what is blocking access.

I see lots of records like this

29 Oct, 2020 09:58:44 Allow United States 66.249.87.108 Firewall rules

as i understand it says that it is allowed
am i wrong?

Allowed is good.

By default, Cloudflare should let such traffic through, but if you’ve set anything in the Firewall section, such as Firewall rules or high security settings, that might block such traffic. But even then, those actions should show up in the Events Log.

There’s always the chance that the server itself is blocking the traffic because it’s coming through Cloudflare and not Yandex. That’s an uncommon situation, as Yandex is able to crawl Cloudflare sites.