socat on a Debian 12 linux VM for port forwarding - How many concurrent connections can it handle?

Question

I am using socat like this on a Debian 12 VM for port forwarding:

socat TCP4-LISTEN:12345,fork,bind=10.111.111.123 TCP4:123.123.123.123:3302

So then with other VMs I connect to the socat VM local IP:12345 and it gets forwarded to 123.123.123.123:3302

But somehow I noticed some HTTP 500 errors after doing this (never seen them before), and my guess is the service got some concurrent connections that caused the 500 error.

PS: a Nginx + PHP8 service connects to the socat for port forwarding.

Questions is: how many concurrent connections can socat handle?

I already edited /etc/security/limits.conf like this:

*               soft     nofile           50000
*               hard     nofile           50000

Same for /etc/sysctl.conf at fs.file-max and net.core.somaxconn