By default, when you want to block or allow some IP(s) from your website, you may simply do it as the following rules from .htaccess,
order deny,allow deny from all allow from 126.96.36.199 allow from 188.8.131.52
However, if you are using service like CloudFlare or other CDN service, you can not do like this as Apache do not understand your visitor IP.
To do that, you need to do like rules below,
SetEnvIf X-FORWARDED-FOR 184.108.40.206 allow SetEnvIf X-FORWARDED-FOR 220.127.116.11 allow order deny,allow deny from all allow from env=allow
If you need it for IP ranges or network block such as 18.104.22.168/24, you may do it like,
SetEnvIf X-FORWARDED-FOR "^1\.1\.1\.*" allow order deny,allow deny from all allow from env=allow