The answer is actually "just use OpenBSD". I work for a local ISP and reinstalled all the aging OpenSUSE boxes with OpenBSD almost 5 years ago. Zero issues and peace of mind, because you know your servers can take care of themselves while you're on vacation. (I've started with OpenBSD around version 5.0 and have witnessed a situation where linux had a bug where whole world was running around with hands in the air and the same issue has been either fixed or mitigated in OpenBSD years ago)
Core of the network is still Cisco and Nokia boxes, but all the support/servery stuff runs on OpenBSD - ELK stack, nextcloud servers, db servers, smokeping, nagios, syslog, tacacs, rpki validators, mail relay.s - you name it.
Only exception is backups servers, where we use TrueNAS with ZFS (FreeBSD-based).
I was testing 10gig SFP+ NICs (intel, broadcom) in linux, freebsd and openbsd with iperf3. I was seeing line rate in linux and freebsd and somewhere around 3gbps in OpenBSD. So while linux and freebsd has top performance, OpenBSD's performance with security mitigations enabled by default is good enough(tm) in most cases.
YMMV
Core of the network is still Cisco and Nokia boxes, but all the support/servery stuff runs on OpenBSD - ELK stack, nextcloud servers, db servers, smokeping, nagios, syslog, tacacs, rpki validators, mail relay.s - you name it.
Only exception is backups servers, where we use TrueNAS with ZFS (FreeBSD-based).
I was testing 10gig SFP+ NICs (intel, broadcom) in linux, freebsd and openbsd with iperf3. I was seeing line rate in linux and freebsd and somewhere around 3gbps in OpenBSD. So while linux and freebsd has top performance, OpenBSD's performance with security mitigations enabled by default is good enough(tm) in most cases.
YMMV