> IPv4 is perfectly and objectively fine on internal networks. IPv6 is overkill and way too complicated for most.

Unless there's a merger/acquisition and the two companies both use 10.0.0.0.

Most home networks use 192.168, and so you can't use that in corporate environments, because the WFH people who VPN in could then have routing snags between local and remote locations.

Also, in your VPN software be sure to perhaps not use 172 addresses (like my previous job did), as some of those ranges are used by Docker by default, and so you can cause issues for developers.

But other than that IPv4 RFC 1918 is not complicated at all…