Dear TP-Link Support Team,

I would like to report a persistent WAN connectivity issue observed on my Archer AX73 router. I hope the details below may help your engineering team investigate a potential firmware-related behavior.
 

Network Topology

Fiber ONT (ISP modem/router) → Ethernet → AX73 WAN port → LAN / WiFi devices

The ISP modem operates in router mode and the AX73 is placed in the modem's DMZ.

There are no switches, extenders, or intermediate devices between the ISP modem and the router.
 

WAN Configuration on AX73

WAN connection type: DHCP (IP assigned from ISP modem via DMZ)
 

Description of the Issue

Over the past several days, the router has been experiencing intermittent WAN interruptions. Each interruption lasts only a few seconds but occurs repeatedly throughout the day. The router itself does not reboot and the connection typically restores automatically.
 

The system log frequently records entries similar to the following:

backup: switch network to WIRED
Led Controller INFO: Start to run WAN0_OFF
Led Controller INFO: Start to run WAN0_ON

These events appear to indicate that the router detects a temporary loss of the Ethernet link on the WAN interface and then immediately re-establishes the connection.
 

In some cases, multiple events occur within a short period. For example:

16:01
16:03
16:04
16:05
16:10
16:12
16:18
16:25
16:30

This pattern resembles Ethernet link renegotiation or link flapping behavior.
 

Additional log patterns also appear repeatedly:

Example – WAN link state changes

2026-03-06 08:47:22 Led Controller INFO Start to run WAN1_OFF
2026-03-06 08:47:24 Led Controller INFO Start to run WAN0_ON
2026-03-06 08:47:31 Led Controller INFO Start to run WAN1_ON

Example – Internet detection / fallback module

2026-03-06 18:02:20 3G4G DEBUG backup: switch network to WIRED
2026-03-06 16:58:12 3G4G DEBUG backup: switch network to WIRED
2026-03-05 13:20:00 3G4G DEBUG backup: switch network to WIRED
 

Troubleshooting Steps Already Performed

To isolate the cause, the following checks were performed:

1. Ethernet cable replacement Multiple Cat6 and Cat7 cables were tested.

2. ISP modem LAN port testing Different LAN ports on the ISP modem were tried.

3. Router power verification The router uses the original power adapter and is operating in a well-ventilated environment.

4. WAN speed negotiation test The WAN port was manually limited to 100 Mbps Full Duplex to test whether the issue was related to Gigabit auto-negotiation. The link flapping behavior still occurred.

5. ISP verification ISP technicians inspected the connection and confirmed that the fiber signal level is stable (approximately -19 dBm). According to their checks, there were no outages or instability detected on the ISP side.
    

Observation

Based on the tests above, the issue may be related to how the router detects WAN connectivity or handles Ethernet link state transitions.

In particular, the following behavior may be worth reviewing:

• The WAN interface appears to reset briefly even though the ISP connection remains stable.
• The Internet detection / fallback module repeatedly logs “switch network to WIRED.”
• Multiple link state transitions can occur within seconds.

This may suggest that the WAN detection logic or Ethernet link monitoring may be triggering reconnection events under certain conditions.
 

Request

I would greatly appreciate if the TP-Link team could review this behavior and determine whether it may relate to:

• WAN PHY driver behavior
• Ethernet auto-negotiation handling
• Internet detection or failover logic
• firmware stability on the WAN interface

If helpful for investigation, I would be happy to provide additional system logs or testing results.

Thank you very much for your time and support. I look forward to your feedback.

Best regards.