>their version of windows seems to require an ipv4 adddess on an interface

Could be DirectAccess. Microsoft's earlier built-in VPN solution before Always On VPN. DirectAccess works only with IPv4 inbound so you can't use IPv6 only stack. Under the hood it uses a combination of v4-v6 transition and translation protocols, but it still requires the Windows client machines to have IPv4 addresses.

If you can run PowerShell commands on the laptop and if "Get-DnsClientNrptPolicy" returns some DirectAccessDnsServers then it's DA laptop.