Wordpress How many concurrent connections ( Approximately ) for Wordpress

Depends on underlying server hardware powering those KVM VPSes and how it's configured LEMP stack wise - latest Centmin Mod 123.09beta01 is heavily optimised and auto tunes it's base settings to the server environment it detects in terms of linux kernel, cpu, memory and disk I/O etc. Also depends on disk usage requirements, sometimes you need higher VPS plans just for disk usage requirements - ensure you read minimum/recommended disk usage requirements for Centmin Mod itself on official install page at https://centminmod.com/install.html

Example same Digitalocean droplet VPS plans on 2 instances have vastly different cpus powering them and performance was dramatically different at DigitalOcean - Benchmarks - DigitalOcean US$15/month droplet benchmarks - Intel Xeon E5-2630Lv2 vs Intel Xeon Gold 6140 - so newer cpus the better

Centmin Mod 123.09beta01's centmin.sh menu option 22 wordpress installer also is heavily optimised for performance with it's 3 choices of full page caching - see Wordpress - Differences between Wordpress regular install vs centmin.sh menu option 22 install

Demo of such wordpress is install is my Wordpress7 site on 2GB DigitalOcean KVM VPS with benchmarks going back to 2014 if you read all the blog posts.

With that said, Centmin Mod users have reported in the past using Centmin Mod 123.09beta01's centmin.sh menu option 22 install with selected cache has allowed a 512MB KVM VPS to handle up to 90,000 unique IP visitors/day or around 2.7 million unique IP visitors per month

My Wordpress7 site on 2GB DigitalOcean KVM VPS using Centmin Mod 123.09beta01's centmin.sh menu option 22 wordpress installer with both Wordpress Super Cache and now Redis Nginx level cache has handled 240 - 300+ million hits/day with 5,000 to 10,000 concurrent visitor benchmarks and I've seen KeyCDN Cache Enabler also handle around the same for Centmin Mod 123.09beta01 on 1-2GB KVM VPS but all these are on at least 2 cpu cores not 1 cpu core which will be less.

So Centmin Mod 123.09beta01 on CentOS 7 with 1GB KVM VPS, with centmin.sh menu option 22 wordpress auto installer and one of the offered full page caches without Cloudflare probably can handle between 500-5,000 concurrent connections easily per cpu thread depending on underlying cpu hardware i.e. cpu model. And then add Cloudflare in front for static file caching, you can probably quadruple that number to around 2,000 to 20,000 concurrent connections per cpu thread - again depending on underlying cpu hardware i.e. cpu model.

This is provided Wordpress full page caching for guests is working. The numbers change if you're predominantly a member logged in non-guest traffic type of Wordpress site as full page caching for guests won't help so you'd need much beefier and higher end VPS and server hardware.

And finally, follow and utilise as many of the performance boosting options in Centmin Mod 123.09beta01 and newer versions as outlined at How To Boost Centmin Mod LEMP Stack Performance i.e. PHP 7 with Profile Guided Optimizations (PGO) and PGO training. See examples of PHP 7.3 + PGO training further down in PHP benchmark thread at PHP - PHP 7.3 vs 7.2 vs 7.1 vs 7.0 (PHP-FPM) Benchmarks

Hope that helps