Technical Analysis and Repeatable Evidence of DHCP/Routing Bug in Netgear Orbi 971 (Router Mode)

Summary of Issue

In environments using the Orbi 971 system in router mode, certain iOS/iPadOS devices (tested: iPhone 16 Pro Max and iPad Pro 2024) sporadically exhibit a failure state in which the device:

Remains physically connected to the Orbi Wi‑Fi network (SSID displays as connected),
Maintains a strong Wi‑Fi signal with excellent throughput (700–1200 Mbps),
Yet silently fails over to the cellular interface (e.g., 5G), with no data traversing the Wi‑Fi path.

Others on the Netgear forums over the past months have posted similar failures, using both Apple and Android devices. My analysis and solution may be correct for other non-Apple devices and other Orbi routers.

This failure is not associated with actual signal loss and does not trigger any user notification other than the UI-level switch from Wi‑Fi bars to a 5G indicator. It self-recovers after 1–2 minutes.

No other devices on my network (macOS, smart TVs, Windows laptops) display similar behavior.

Summary of Solution

For any device exhibiting drops/flips to cellular when on a good WiFi signal, change IPv4 address to a manual address, outside the router’s DHCP range.
Also, change DNS address to a manual entry – it can either be your router (192.168.1.1 usually) or a 3^rd party DNS server of your choice.
Finally, you must disable IPv6 on the 970 router – Advanced tab, expand the Advanced section in the sidebar, choose IPv6 and disable.

To learn more as to what the problem may be, read on.

My Environment

Netgear Orbi 971 (Wi-Fi 7), latest stable firmware (9.13.1.2) as of July 2025.
Router mode (default DHCP and NAT).
IPv6 disabled at the router level.
iPhone and iPad running latest iOS/iPadOS 18.5.
Orbi system is sole DHCP and DNS provider on LAN.
WAN is Comcast/Xfinity (stable, no packet loss during tests, 2100/300 dl/ul plan).
Orbi clients tested within 15 feet of router or satellite in clear line-of-sight — eliminating signal strength as a factor.

Problem Behavior

When in default DHCP configuration (automatic IP and DNS):

iOS devices periodically experience a silent failover to cellular (5G).
Devices retain visible SSID connection.
Internet connectivity is routed over cellular until the issue self-resolves.
The issue is sporadic, occurring 1–5 times per week for me (others have seen higher failure rates) under default conditions.
Disruptions have been reported on non-iOS devices on the Netgear forums.
I wrote and tested an Apple Shortcuts automation that will trigger when the Apple device it is running on does a Wi‑Fi disconnect. It does not fire, confirming that SSID association is intact.

Testing Methodology and Key Finding

I conducted controlled testing to isolate the failure cause. After numerous incidents in DHCP mode, I applied the following configuration to both iPhone and iPad:

Manually assigned IPv4 address within the LAN’s valid range (outside the DHCP pool to avoid collision).
Manually assigned IPv4 DNS server set to 192.168.1.1 (Orbi’s own LAN IP).
IPv6 explicitly disabled at the router.

This configuration has now been running for over 5 consecutive days as of the date of this posting, with no recurrence of the issue. Devices have remained on Wi‑Fi, and no visible or functional failovers to cellular occurred.

Why Disabling IPv6 Was Critical

On iOS and iPadOS, users cannot manually configure IPv6 addresses or DNS servers via the system interface. As a result, if IPv6 remains enabled on the network:

iOS will continue to obtain IPv6 connectivity using SLAAC or DHCPv6 (often via Router Advertisements from the Orbi),
Even if IPv4 is statically assigned, IPv6 may still be selected for outbound traffic when iOS considers it preferred (which is often),
This reintroduces reliance on the Orbi’s IPv6 DHCP or routing stack, which in prior testing exhibited instability and routing failures, often leading to connectivity loss or fallback to cellular.

Thus, disabling IPv6 at the router level is a necessary precondition to ensure the device fully relies on the statically configured IPv4 path — eliminating Orbi-managed DHCP lease/route state from the equation entirely.

Theory: Root Cause Analysis

I propose the following sequence of events under default DHCP operation:

iOS frequently initiates DHCP lease renewal or INFORM messages more aggressively than other OSes (due to roaming, sleep/wake cycles, and Apple’s proactive network health checks).
The Orbi 971’s DHCP server intermittently fails to respond promptly (or at all) to these renewal or rebind requests.
During this silent DHCP stall, the iOS device:

Still has a valid SSID association and a cached IP,
But considers the Wi‑Fi interface non-functional due to:

Missing or expired lease,
Failure to renew default gateway,
Unsuccessful DNS resolution,
Or failure to receive HTTP 204 from captive.apple.com.

iOS silently switches to cellular, even with Wi‑Fi Assist disabled (which I did a long time ago), because it considers the Wi‑Fi path “connected but unusable.”
Eventually, the Orbi responds again, routing is restored, and iOS resumes Wi‑Fi traffic — all without disconnecting or notifying the user.

Supporting Factors

No failure symptoms observed under static IPv4 + DNS configuration with IPv6 disabled.
Monitoring showed no WAN outage or SSID drop during incident periods.
When using dynamic DHCP/DNS, the issue persists in high signal-strength environments, ruling out RF-related causes.
IPv6 had previously been associated with similar instabilities and was disabled early in the test cycle.

Recommendations to Netgear Engineering

I recommend the following areas be prioritized for investigation:

DHCP Server Responsiveness

Analyze handling of frequent DHCP RENEW/INFORM messages from Apple devices.
Investigate whether ACK or lease confirmations are being dropped or delayed.

Internal Lease Table Integrity

Confirm whether memory or timing issues affect DHCP state or ARP caching.

Routing Table Consistency

Validate propagation of default routes across mesh nodes, especially post-roaming or post-sleep.

IPv6 Handling (if re-enabled)

Evaluate Router Advertisement stability and DHCPv6 consistency.
Provide user-accessible controls for IPv6 lease time and DNS relay.

Debug Logging Tools

Enable deeper client-specific DHCP logging in future firmware versions to support field diagnosis.

Conclusion

The silent failover of iOS devices to cellular, despite strong Wi‑Fi signal, appears to be rooted in intermittent failures of DHCP IPv4/IPv6 or routing state management by the Orbi 971. Disabling IPv6 and bypassing DHCP/DNS with manual configuration eliminated the issue so far — confirming the failure lies not in radio or ISP connection, but in the Orbi’s handling of dynamic IP and DNS lease logic under typical iOS behavior.

I welcome the opportunity to collaborate on further testing or provide supplemental logs to support engineering review.

Forum Discussion

Device flipping to celllular/disconnecting when on WiFi? Read this for possible solution!