A WAN port that reports no Ethernet link needs a physical test before an IP configuration change.
Before you change anything
This is a diagnostic entry point. The source supports the general check, not a confirmed root cause for your device.
What to check first
Does the same failure occur on a wired client connected to the router?
Record the exact model, hardware revision, firmware and recent change before adjusting settings. If you cannot answer the question, keep the cause open.
Narrow the likely path
| Observation | Next check |
|---|---|
| WAN link is down | Inspect the modem/ONT, Ethernet cable, intended WAN port and provider status. |
| WAN address is absent | Check the ISP connection type and upstream gateway without changing Wi-Fi settings. |
| WAN address exists | Separate DNS-only failures from total upstream failures. |
Decision after the first test
Check the modem or ONT Ethernet port, cable seating, link LEDs and intended router port. Try one known-good cable without forming a second loop.
Use a documented next step
Verify before escalating
After each change, repeat the exact failed task. If the result is unchanged, restore the previous setting and use the official support link for your exact hardware revision. Don’t assume a menu or capability from a related model.
Official sources
- TP-Link RE900XD US specifications (web_text; checked 2026-11-01)
Check your exact US model, hardware revision, and firmware on the linked support page before changing settings.