After days of troubleshooting I think I found that Cloudflare is blocking access to m4a audio files for the users who visit my website from their mobile devices. Like an iPhone. For example, the link below works fine on Chrome Windows x64. But the same file does not play in Safari/Chrome on my iPhone 8. A black background shows up and there is a crossed Play button in the middle.
I know the culprit is the Cloudflare because as soon as I pause Cloudflare the issue goes away.
I tried Page Rules to bypass cache, performance etc for the subfolder “d” and everything below it. But it didn’t help.
Could you please help? This is a serious issue for us.