ERR_SSL_PROTOCOL_ERROR for some users on subdomain – works fine for others

[partha]

What is the name of the domain?

Formester

What is the error message?

This site can’t provide a secure connection application.formester.com sent an invalid response. ERR_SSL_PROTOCOL_ERROR

What is the issue you’re encountering

We’re encountering an intermittent issue with few of our subdomains. One of those are application.formester.com. For some users, the site loads fine and serves over HTTPS without any issues. However, for others, it throws the following error in Chrome: This site can’t provide a secure connection application.formester.com sent an invalid response. ERR_SSL_PROTOCOL_ERROR We’ve confirmed this isn’t a browser cache issue, and it’s reproducible for some users consistently while others never see the problem. This seems to be impacting users inconsistently across regions/devices. Any guidance or help in troubleshooting this further would be greatly appreciated.

What feature, service or problem is this related to?

DNS records

Screenshot of the error

[sjr]

application is not proxied through Cloudflare so any SSL issue you will have to check at your origin/host…
https://cf.sjr.dev/tools/check?17f09ef7bebb4cc79665c6c5375a13af#dns