Frequently Asked Question
My UniFi gateway has an Ethernet link but no internet after replacing the ISP router. What should I check?
QUICK ANSWER
An active port proves only the physical link. The correct WAN role, ISP connection method, VLAN and provider handoff are still required. Keep the original working settings before changing the gateway.
Applies to: UniFi gateway WAN setup or remapping; ISP-specific values must come from the actual service provider.
Work through these checks
- Record the old router’s working connection type and the provider’s handoff details. Distinguish an ONT, a routed ONR and a bridge-mode modem; they do not necessarily present the same connection to your gateway.
- In Network > Settings > Internet, confirm the cable reaches the port assigned to the intended WAN. Check its link state and whether it obtained an address, gateway and DNS settings.
- Match DHCP, static addressing or PPPoE to the provider’s documented service. Apply a WAN VLAN only when required, using the exact supplied value. Do not copy another customer’s ISP VLAN or credentials.
- Test from a wired LAN client. Separate failed external connectivity from DNS-only failure and from a single VLAN’s routing policy. If restoring the original router works, retain both sets of results for the provider or Specialist.
Confirm the result
The gateway shows the intended WAN active and authorised LAN/VLAN clients can reach the required services with normal DNS resolution.
Before going further: Changing WAN roles interrupts service. Do not reset the ONT/ONR, bypass an ISP’s required equipment or alter optical settings without the provider’s instructions.
If you need help
Include these details in your ticket: Gateway/Network versions, provider service type, redacted WAN status, physical diagram and comparison with the original router.
Updated 261107