LAN stops working after unplug WAN cable from Deco X20-4G

LAN stops working after unplug WAN cable from Deco X20-4G
LAN stops working after unplug WAN cable from Deco X20-4G
2022-04-29 09:53:09 - last edited 2022-07-12 02:37:13
Hardware Version: V1
Firmware Version: 210708

This article applies to

Deco X20-4G



On the Deco X20-4G, there are three operation modes: Wireless Router mode, 3G/4G Router mode and Access Point mode. When it works in Wireless Router mode, you can use the 3G/4G network as a backup solution for internet access so that your Deco will switch to the 3G/4G network when the WAN connection fails.


Network Topology

Internet----Modem/Main Router----Deco X20-4G(with SIM card inserted)----PC or Smartphones

Note: Deco X20-4G is using Wireless Router mode with 3G/4G Backup enabled


Possible issues:

Some customers might try to unplug the cable between Modem/Router and Deco X20-4G after Deco failover to 3G/4G backup successfully, then find Wi-Fi work fine but LAN connection stop working and wired clients are unable to obtain IP addresses.


Root Cause

All the Ethernet ports on Deco support WAN/LAN auto-sensing, when the Ethernet WAN works, the other ports are LAN ports, thus LAN are working fine.

However, if you unplug the Ethernet WAN cable from Deco, there will be no fixed WAN port any more, and the Deco will need to always detect the status of all the WAN/LAN ports to confirm whether it failover back to the Ethernet internet from 3G4G backup. Therefore, there is no fixed WAN or LAN ports during those time, that is to say, all the ports are WAN ports, thus LAN connection would be disconnected.



1. Please keep the physical connection linked up. When internet access of your Ethernet WAN fails, Deco will still switch to 3G/4G backup, and since WAN/LAN port status on Deco does not change, the LAN will keep working fine.

2. If you would like to fix the WAN port when enabling 3G/4G backup, please try the following beta firmware, which will fix the bottom port to be WAN port after enabling 3G/4G backup: Deco X20-4G 20220429

Note: If 3G/4G backup is not enabled, all the ports are still WAN/LAN auto sensing.