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X20-4AG Troubleshooting 3G/4G Backup

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X20-4AG Troubleshooting 3G/4G Backup

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X20-4AG Troubleshooting 3G/4G Backup
X20-4AG Troubleshooting 3G/4G Backup
2022-11-14 18:02:54 - last edited 2022-11-16 01:21:40
Tags: #Highlighted Thread #3G/4G Backup
Model: Deco X20-4G  
Hardware Version: V1
Firmware Version: 1.0.5 Build 20210708 Rel. 64376

I have added a X20-4AG to an existing Deco network (3 x Deco M4R) and set it as the Main Deco with Operation Mode Wi-Fi-Router. All is working fine with no issues.

 

Then I inserted a nano SIM as I need failover. However, as soon as I switch on 3G/4G Backup:

  • the whole network indicates that there is no internet (LED is Red on all Deco units) even though there is and it is working
  • SIM Card Status shows as No SIM
  • most operations result in a "Failed" error which I assume is because it is not detecting the SIM

 

To be clear, the SIM does work. I have tested it in a mobile phone. It's activated and works fine. It's just not recognised by the X20. I thought maybe I need to add APN settings but per the above, trying to do so results in a "Failed" error as soon as I choose the option.

 

Is there an issue here in terms of set up? Should I have set it up in 3G/4G Router mode first?

 

It's quite frustrating so any help would be appreciated.

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#1
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1 Accepted Solution
Re:X20-4AG Troubleshooting 3G/4G Backup-Solution
2022-11-15 18:58:48 - last edited 2022-11-15 19:51:42

So quick update. I decided to rebuild the network (groan):

 

  • I reset the X20-4G
  • I created a new network in Operation Mode > 3G/4G Router with the nano SIM inserted. That worked with no issues. The SIM card was recognised and I have data and internet through it :)
  • I set the X20-4G to Operation Mode > Wireless Router with the ethernet WAN connected. I was able to put in the PPoE details and that worked fine.
  • I then enabled 3G/4G Backup and all the SIM setup details that were there before were there! AND crucially the LED is green not red :)
  • I set Offline Detection > Dual and then simulated a failover by pulling out the ethernet WAN connection. Failover to 3G/4G took a few seconds and then it worked! I could see in the Deco App that the X20-4G was "Online (3G/4G Backup)".
  • I plugged the ethernet WAN connection back in. Failback to ethernet WAN worked. I could see in the Deco App that the X20-4G was now "Online".

 

So my conclusion is The SIM card must be set up FIRST using 3G/4G Router mode before the WAN connection is set up and 3G/4G Backup is enabled.

 

Of course, I'm having a new problem now. I can't add the old Decos back to this new network despite resetting and them pulsing Blue!

 

If I still have problems, do you suggest carrying on in this thread? Or creating a new one?

 

But I'm happy that my failover to 3G/4G is working - that was the raison d'etre for buying the X20-4G in the first place!

 

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Re:X20-4AG Troubleshooting 3G/4G Backup
2022-11-15 06:40:22

  @Emanur Hi, Thanks for the feedback. 

May I know your SIM card service provider?

 

Then I inserted a nano SIM as I need failover. However, as soon as I switch on 3G/4G Backup:

  • the whole network indicates that there is no internet (LED is Red on all Deco units) even though there is and it is working

Do you mean even the current main Ethernet WAN connection is still active, the main Deco would still turn to solid red, right?

At this moment, if you go back to Deco APP>More>Advanced>IPV4, would Deco still get an IPV4 address here?

 

By the way, can I have a picture of your current network layout, such as:

Main Internet ISP--- Deco X20-DSL---network switch---3*satellite M4s

Wait for your reply..

Best regards.

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#2
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Re:X20-4AG Troubleshooting 3G/4G Backup
2022-11-15 10:43:13

  @David-TP Many thanks for responding. So, to your questions:

 

Yes, even though the ethernet WAN is active and confirmed to be working the main Deco turns to solid red.

 

I wasn't able to carry out the IPV4 test as I have a new problem!

  • When I go to Deco App>More>Advanced>Operation Mode>3G/4G Backup, the toggle to enable it is disabled. Before this I could use the toggle and see the other parameters including SIM Status etc. Now there is nothing.
  • All the satellite Decos are all now showing as disconnected

 

The current network layout is: Main Internet ISP --> Deco X20-4G+ (using PPoE) --> 3 x Deco M4 satellites. There are no hardwired connections. All devices connect via the WiFi.

 

I'm hoping I don't have to trash everything and start again!

 

Especially in the middle of the working day...

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#3
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Re:X20-4AG Troubleshooting 3G/4G Backup-Solution
2022-11-15 18:58:48 - last edited 2022-11-15 19:51:42

So quick update. I decided to rebuild the network (groan):

 

  • I reset the X20-4G
  • I created a new network in Operation Mode > 3G/4G Router with the nano SIM inserted. That worked with no issues. The SIM card was recognised and I have data and internet through it :)
  • I set the X20-4G to Operation Mode > Wireless Router with the ethernet WAN connected. I was able to put in the PPoE details and that worked fine.
  • I then enabled 3G/4G Backup and all the SIM setup details that were there before were there! AND crucially the LED is green not red :)
  • I set Offline Detection > Dual and then simulated a failover by pulling out the ethernet WAN connection. Failover to 3G/4G took a few seconds and then it worked! I could see in the Deco App that the X20-4G was "Online (3G/4G Backup)".
  • I plugged the ethernet WAN connection back in. Failback to ethernet WAN worked. I could see in the Deco App that the X20-4G was now "Online".

 

So my conclusion is The SIM card must be set up FIRST using 3G/4G Router mode before the WAN connection is set up and 3G/4G Backup is enabled.

 

Of course, I'm having a new problem now. I can't add the old Decos back to this new network despite resetting and them pulsing Blue!

 

If I still have problems, do you suggest carrying on in this thread? Or creating a new one?

 

But I'm happy that my failover to 3G/4G is working - that was the raison d'etre for buying the X20-4G in the first place!

 

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#4
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Re:X20-4AG Troubleshooting 3G/4G Backup
2022-11-15 19:51:37

I've sorted out the problem. One of the old Decos was still active on the old network which had the same SSID as the new one so it was the Deco App getting confused.

 

School boy error if I'm honest.

 

Anyway, all done and all happy now :)

 

However I do think that TP-LINK should document this behaviour so that other buyers know, at least until they've fixed this.

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#5
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Re:X20-4AG Troubleshooting 3G/4G Backup
2022-11-16 01:25:54

  @Emanur 

Thank you very much for the update. Your post is tremendously helpful! I will definitely report to the senior engineers for further optimization.

 

And next time, if you have a new problem, you could open a new thread.

Thanks a lot.

Best regards.

 

 

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#6
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