security – When and how can I use client certificate authentication on iOS?

I have installed a x509/pfx certificate under profiles in my iOS settings and configured my webserver (nginx) to require this certificate. With Safari on iOS, I can browse to my main page using the certificate, but when I try to go to any of my subdomains, I get error 421 Misdirected Request. Chrome does not seem to send the certificate at all (error 400). On the desktop however, everything works as it should.

  • How can I go about debugging the iOS/Safari-specific issues?
  • Can I send a certificate with WebDAV requests?
  • Does each software need to be specifically set up to send client certificates?

I am using an iPhone 8 Plus with with iOS 14.3