If you share that link into our demo site http://easysocial.stackideas.com/ then it work fine, mean that is probably because of your site security issue, perhaps you can consult with your webhosting provider regarding this (Sucuri WebSite Firewall - Access Denied) and see how it goes?

To quickly identify this, you can temporary turn off this "Sucuri WebSite Firewall" then share that link again on the site and see whether it still show the same access denied error.

I wrote about hosting yesterday and replied that the problem is in the application. I tried to insert the link now here at your site and the same problem "Sucuri WebSite Firewall - Access Denied". These are links from this site, an example:
https://aeronet.cz/news/gott-mit-uns-v-nemecku-jednoznacne-ale-doma-a-na-slovensku-je-to-sok-byvaly-sef-lidovcu-se-navezl-do-karla-gotta-na-twitteru-politicky-komentator-mistrovi-vycetl-socialistickou-druzbu/

Basically it not only blocked your site, it probably blocked other crawler except those famous crawler site like Facebook, Linkedin an etc.

Translated by Google:

Thank you. I wrote to https://aeronet.cz administrator and they answered me:

"This is a report from our firewall that does not allow our server resources to be used for IP addresses that are missing a valid DNS reverse record. Your IP address from Malaysia is reported in the international database as an IP address used to commit cybercrime. This is obviously the VPN range that hackers use in Asia to attack. Therefore, the IP address lacks a DNS record. It returns only the generic pool record ns2.tm.net.my, which does not identify the IP address, but the entire name server."

https://apps.db.ripe.net/db-web-ui/#/query?searchtext=175.136.212.122
https://mxtoolbox.com/SuperTool.aspx?action=ptr%3a175.136.212.122&run=toolpage

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Original message

Děkuji. Psal jsem na web https://aeronet.cz administratorovi a odpověděli mi:

"Toto je hlášení našeho firewallu, který nedovoluje používat zdroje našeho serveru pro IP adresy, kterým chybí reverzní záznam v DNS v korektním tvaru.Vaše IP adresa z Malajsie je nahlášena v mezinárodní databázi jako IP adresa používaná k páchání kybernetické kriminality. Jedná se zjevně o VPN rozsah, který v Asii používají hackeři ke svým útokům. I proto IP adresa postrádá DNS record.Vrací pouze generický pool record ns2.tm.net.my, který neidentifikuje IP adresu, ale celý name server."

https://apps.db.ripe.net/db-web-ui/#/query?searchtext=175.136.212.122
https://mxtoolbox.com/SuperTool.aspx?action=ptr%3a175.136.212.122&run=toolpage
==

Hey Pavel,

I am really sorry for the delay of this reply as it is a weekend for us here.

Yes, I've trying to crawl that article page using my localhost IP address, may i know is it they manage to resolve this when people share the link on your site?