How do I compare IPv4 and IPv6 connectivity from Windows?
A hostname can resolve to both IPv4 and IPv6 while only one path works correctly. Test the address families separately and compare the actual service results. This identifies a broken path without changing system-wide networking.
Instructions
1. Check both DNS record types
Confirm that the expected address is published for each supported family.
Resolve-DnsName vps.example.com -Type A -DnsOnly
Resolve-DnsName vps.example.com -Type AAAA -DnsOnlyA missing AAAA record can be intentional; only test a family that the service is meant to support.
2. Try SSH with an explicit address family
Use normal authentication and host verification for both attempts.
ssh -4 -o ConnectTimeout=10 adminuser@vps.example.com
ssh -6 -o ConnectTimeout=10 adminuser@vps.example.comRun each as a separate diagnostic attempt. Exit a successful interactive session before starting the other test locally.
3. Investigate the failing family
Compare routing, firewall rules, listener bindings and published records for that family. A temporary per-command -4 option can isolate the issue, but it does not repair an incorrect IPv6 deployment.
Check the result
- Each intended address family reaches the correct verified service.
- DNS, listener and firewall settings agree with the service’s intended IPv4 or IPv6 support.
Troubleshooting
- IPv4 works and IPv6 times out
- Check whether the client network has IPv6 and whether the server’s IPv6 route and firewall are configured.
- The two families show different host identities
- Confirm that both DNS records actually point to the intended server before accepting any new key.
Official references
Use the documentation for your installed version when a flag, service name or platform feature differs.