This incident involves Cloudflare network and JIO network, basically IPs are being involved.
The fix also revolves around Cloudflare and our IP ranges communicating with JIO.
- Review origin web server error logs to identify web server application crashes or outages.
- Confirm Cloudflare IP addressesOpen external link are not blocked or rate limited
- Allow all Cloudflare IP rangesOpen external link in your origin web server’s firewall or other security software
Try a dig to your domain.
You should see the Cloudflare Anycast IPs.
Try a trace route or MTR to the Anycast IPs.
When you see a Cloudflare error page this means Cloudflare is able to reach your Origin to get the 521 displayed. The next step is to test if the return route is working out.
Thank you.