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

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

SolutionLAN 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
Model: Deco X20-4G  
Hardware Version: V1
Firmware Version: 210708

This article applies to

Deco X20-4G

 

Background

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.

 

Solution

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.

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#1
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6 Reply
Re:LAN stops working after unplug WAN cable from Deco X20-4G
2022-10-24 08:55:22 - last edited 2022-10-24 10:34:40

Hi  @Sunshine  

I have a simple configuration

fiber <-> (isp router) <-> X20-4G <-> Switch with PCs

X20-4G is Wireless Router mode with 3G/4G Backup enabled

I have trouble with my LAN network because of WAN/LAN auto-sensing, and I discover and test the beta firmware for fixing the WAN port, great news and good idea !

 

Share my experience after applying the firmware 1.0.5 Build 20220429 Rel. 53841

1 - I plug my isp router on port 3 of X20 - 192.168.5.0/24

2 - I plug my switch on port 2 f X20 - 192.168.168.10.0/24

3 - Activate 4G backup.

4 - All works fine.

5 - Simulate a failover by power off fiber.

6 - Backup 4G works fine. All works fine.

7 - Test failover back to ethernet by power on fiber, and the X20G never recover it, always works on 4G backup.

8 - Reboot X20 same isssue, the unit stay on 4G connexion.

9 - I found to swith off manualy backup mode for recovery the ethernet connexion, enable then backup mode.

10 - Rebooting X20 force 4G connexion... for me it's a mistake 

 

Am i right ? or lost an information ?

And I take the opportunity for suggestion, can you send a notification App or Email when failover occurs ?

Thanks in advance,

Regards
 

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#2
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Re:LAN stops working after unplug WAN cable from Deco X20-4G
2022-10-26 03:12:01

  @jerph 

Welcome to the community.

You might refer to this link to change the offline detection to dual detection to see whether it helped or not:

https://community.tp-link.com/en/home/kb/detail/412570

Best regards.

 

Deco Monthly Recap- Check What's Currently Going on With Deco TL-WA850RE V7 Adds the Support of Customizing Password and Encryption Type
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#3
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Re:LAN stops working after unplug WAN cable from Deco X20-4G
2022-10-26 08:09:10

Hi @David-TP !

 

Thanks for your welcome.

I read your kb, my configuration is fine except that I set up an ip other than 0.0.0.0 for dual detection, I had put 1.1.1.1, I have return it to default.

So if I reboot X20, the traffic goes on fiber, right.

 

Simulate a cut of fiber on my isp router, it failover to 4G backup successfully.

But now, traffic stay in the backup mode 4G even if I recover the fiber, even if I reboot X20...

The only action that i can do to recover the fiber is to manually disable/enable backup 4G

 

I made an other test, physically disconnecting the cable on WAN port 3 on X20, switch backup 4G works fine, repluging the cable switch rollback to fiber -> perfect

 

My case is really like this in kb "When the main WAN fails, it failover to 3G/4G backup successfully, however, when the main recovers, it still stays on the backup internet."

 

Thanks for your support

 

 

 

 

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#4
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Re:LAN stops working after unplug WAN cable from Deco X20-4G
2022-11-04 06:28:37

 

jerph Hi, Sorry for the inconvenience and after consulting with the senior engineers, I would like to follow up on your case by email and please check whether you have got an email from me.

 

@CoreAI , It does work with the external LTE antennas. As for the failover time, It depends not only on the modem but the LTE SIM provider. Normally one round of failover detection of the modem takes about 30s and Within one minute is quite acceptable.

Thank you very much.

Best regards.

Deco Monthly Recap- Check What's Currently Going on With Deco TL-WA850RE V7 Adds the Support of Customizing Password and Encryption Type
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#6
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Re:LAN stops working after unplug WAN cable from Deco X20-4G
2022-12-22 15:05:49 - last edited 2022-12-22 17:47:31

  @Sunshine 

When will this firmware be officially released ? is there a new/updated/patched version since april 2022 ?

This is a critical issue for me. It has to be fixed, or the product sent back.

 

Thanks in advance.

 

EDIT : this patch is working really well for me. Failover to 4G and switch back to wired internet is fine. Thanks a lot. Now waiting for an official release

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#7
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Re:LAN stops working after unplug WAN cable from Deco X20-4G
2023-10-20 09:11:18 - last edited 2023-10-21 06:34:28

  @Sunshine 

This is not only 4G model problem.

 

I have Raspberry Pi on other port and internet modem on the other. Raspberry Pi handles home automation and idea is to keep deco's wifi running and Rasperry controlling home even if internet fails. If modem shuts down Rasperry should continue controlling but what happends is that deco drops Rasperry Pi from the line. Not acceptable!

 

On the Deco controlling application must have possibility select the wan port permanently!

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