This is something that sometimes is happening to me when I use the WordPress app from the mobile to upload a post.
On Apache there is a software called ModSecurity that prevents from attacks to the web and blocks the IPs when there are recurrent errors.
The problem is when your IP is the one that cannot access to your own web or your admin.
To fix it: https://www.inmotionhosting.com/support/edu/cpanel/how-to-disable-modsecurity-cpanel/
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