Add people, not invoices
Pritunl editions and what the free tier covers
Pritunl is an open source VPN server with a web interface built for administrators rather than for one person with a config file. It speaks OpenVPN, WireGuard and IPsec, so a laptop connects with a standard client while a datacenter link uses whichever protocol suits the route. Users get their own accounts and profiles, two-factor is available on every one of them, and removing somebody who left takes a click instead of a rebuild.
The free tier is more generous than people expect. A single Pritunl server, unlimited users, unlimited devices, no registration and no card. Pritunl's paid tiers are priced per server rather than per person, which means the arithmetic that makes commercial VPN products expensive at scale simply doesn't apply here. Premium adds port forwarding and failover. Enterprise adds single sign-on, server replication and site-to-site links. Both come from Pritunl, and both leave the user count uncapped.