@tracy, another issue is that help.dekunu.tech is requesting a client certificate. Your server is probably misconfigured. In nginx config, set “ssl_verify_client off” instead of optional or on.
This happens on mobile devices primarily. Samsung browser and Chrome. Both request client certificates. My phone has two work-related certs installed, and I am always getting prompted for them. Denying it will immediately prompt for cert again. Repeatedly denying on Samsung browser does nothing but show the same prompt. Repeatedly denying on Chrome crashes it.