What this page covers
Use the router’s IPv6 status and provider documentation rather than guessing a prefix size or manual address.
Step-by-step workflow
- Record the IPv6 WAN status and delegation error privately.
- Check whether the ISP requires DHCPv6-PD, PPPoE or another handoff.
- Confirm the LAN has a delegated prefix before changing RA settings.
- Ask the provider if the service supports third-party router delegation.
Decision table
| Check | What it tells you | Safe next action |
|---|---|---|
| No delegated prefix | LAN cannot build its normal global subnet | Check WAN handoff/provider |
| WAN IPv6 only | LAN advertisement may be incomplete | Review router IPv6 mode |
| Prefix changes after reboot | Lease or provider policy may vary | Record dates and source details |
Limits and verification
Exact prefix sizes and WAN values are provider-specific and should never be invented from a generic IPv6 guide.
Official sources
- IETF RFC 8415 — DHCP for IPv6 (DHCPv6 behavior)
- Google Fiber — Use your own router (fiber handoff considerations)
Related Router Portal guides
Router login troubleshooting · Router security guide
Keep in mind: Firmware, operating-system menus, ISP policies and regional radio rules can change. Confirm the current official source and exact device before applying a setting.
Our networking steps are lab-tested against standard RFC 1918 private networking protocols across Windows 11 (24H2), macOS Sequoia (15.1), iOS 18, and Android 15. We verify physical device labels and firmware release documentation before publishing gateway instructions. Router Portal is strictly read-only and never requests, intercepts, or logs router passwords.