Hello, I have an ISPconfig (latest non-3.2 beta) version 3.1.15p3 installed on 2020.jun.08 using: https://www.howtoforge.com/tutorial/ubuntu-ispconfig-automated-install-script/ on Ubuntu 18.04 LTS with NGINX, MariaDb, PHP 7.x (all as the install script prompts me for or auto-selected)... This server is hosting two WordPress sites using SSL (LetsEncrypt). It has been working well with the primary WordPress site until today. I get some web browser users reporting: "ERROR 403 - Forbidden!" on my mobile Samsung Note 8 I get: "ERR_CONNECTION_TIMED_OUT". But on my desktop computer the site loads just fine and loads quickly. I have rebooted the cloud server after applying all Ubuntu updates. The CPU is hovering around 0% or 1%. RAM is 0.75 GB used of 1 GB. (Edit: now using 0.68 GB RAM). This VPS is a high performance instance using SSD disks. It responds quickly to load the WordPress site on my desktop computers (at my IP address and at several remote IPs that I've tested via Remote Desktop). But for many client web browsers (including my Note 8 Android phone on a different IP), it times out and fails to load or shows an ISPconfig page that says: "ERROR 403 - Forbidden!" This is a live, production website. The VPS only has one other website that is a staging site for the main WP site. So, only the one live WP site on this server. Please advise what I can check or how to diagnose/fix the (a) 403 Error displayed by ISPconfig when trying to access the WP site, and (b) the "ERR_CONNECTION_TIMED_OUT". I don't know if (a) and (b) are related. Bottom line, my customers can not access the ISPconfig based WP site. I can provide the website address privately upon request. Thank you.
Check the access.log and error.log of the website when you access it trough a browser to see which error you get. if the site has a lot of traffic, then it can be useful that you try to find out which IP the failing client uses to connect to the server and then grep in the log file for this IP to get only the relevant lines.
