Thank you for your advice, I appreciate it. I did examine everything that came to mind and the only thing at this point that may be happening is cloudflare -> origin connectivity for some users. I am using a keyword based monitoring since day one and so far no issues with reachability have been detected. This could be related to CF Geo firewall (disabled, but perhaps caching on CF side need to expire?). The only way I can verify CF<->Origin connectivity is by paying for CF a Pro account with Origin health check feature. If you have any ideas/suggestions how to troubleshoot this, I would be happy to hear them. Thanks!