I’m a self employed Network Consultant, working with 2 partners (to cover vacations, larger projects and such).
I plan / build and run networks for about 20-30 SME (Small and Medium Enterprises).
All my networks are “on site” for my clients.
All run Proxmox as basis, NethServer in a VM as AD, file, mail, nextcloud and Zabbix monitoring.
I don’t use NethServer as a firewall, this is done with an OPNsense Firewall - just for the reason I prefer having my firewall separate from any other service / hardware and running on independant hardware. I have used NethServer as a firewall, mainly temporary, but it works very well.
Backups are in house, but also daily “Off-Site”. This includes VMs. Backups are generally 7 Generations, Monthly (actually fortnightly, twice a month) backups are saved for several years.
Some clients are running 3 sites, with backups of each site at the other 2 sites.
There is one NethServer as master server for all, all sites have large NAS.
Some clients have HA Internet, with 2-3 Internet providers for redundancy.
Clients are mainly Windows, some are almost entirely Mac based. Very few have Linux desktops (unfortunately).
All networks are working very stable and well at the moment.
My 2 cents