Check the route you're posting to. Pretty common now to drop the www. on domain urls now and possibly not redirecting properly.
Also ensure your assets are downloading via your https too.
I have a site that uses Dropzone for file uploads. My LetsEncrypt SSL certificate was created using Forge. The file upload works fine from desktop but doesn't work on my iPhone. On my iPhone, when I select a file to upload it gets rejected immediately. When I remove the certificate from my site the error goes away and files are uploaded successfully.
Separately, I got an email from Google Search Console Team telling me that my certificate doesn't include the www subdomain, however, when I run an ssllabs test it shows my domain and the www domain as alternative names.
I believe what's happening is on my phone Safari thinks the upload request is being sent by a domain that isn't listed on the certificate. Still figuring out what exactly the issue is but figured I'd post here in case someone else has had a similar issue and knows exactly where to look.
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