Following some [discussion](https://www.turnkeylinux.org/forum/support/mon-20221205-1227/debian-11-turnkey-wordpress-171-1-refusing-connections-ios-devices) and research, it appears that there is an issue (in [Nginx](https://github.com/NginxProxyManager/nginx-proxy-manager/issues/661)? [Safari/iOS](https://bugs.webkit.org/show_bug.cgi?id=218560)? Apache?) when an [Apache server is behind an Nginx reverse proxy](https://serverfault.com/questions/818535/nginxapache2letsencrypt-with-iphone-cannot-display-page). The workaround is to edit the nginx config (for the reverse proxy). First find the location block - it should look something like this: ``` location / { proxy_pass https://BACKEND_SERVER_IP:443; [...] } ``` Then within that (i.e. after the first line and before the closing `}`): ``` proxy_hide_header Upgrade; ```