LB2120 - Keeps switching between 4G and Broadband

[blackeyes]

My LB2120 is connected in bridge mode in between a DSL modem provided by my ISP and another Netgear Wifi router (WNR3500). At the DSL modem level, the broadband connection is very stable. I have reasonable ping times and very decent download and upload speeds. However, I experience frequent failovers of the LB2120 to 4G, even if at the time, my DSL modem internet connection is still fine. For failover detection, I am pinging both Google DNS servers (8.8.8.8 and 8.8.4.4) so that should be no problem. I have setup SMS alerts for both switching to 4G and switching to broadband. And sometimes, I get multiple consecutive SMS for switching to broadband, without any switching to 4G in between. Around the time when this happens, the internet connection from behind the WNR3500 (therefore from behind the LB2120 too) is not working anymore. I don't understand how it could switch to broadband multiple times in a row without going to 4G in between, and why it switches to 4G even if the internet connection at the modem level is fine. Of course, I have tried to restart everything multiple times, I have tried to replace the ethernet cable between the DSL modem and the LB2120, and I have even recently replaced the ISP modem to a new one. Any suggestion please?

[Blanca_O]

Hi @blackeyes

Welcome to NETGEAR Community! 

Have you tried resetting LB2120? 

What is the current firmware version of LB2120? 

Regards, 
Blanca 
Community Team
 

[blackeyes]

Hi @Blanca_O,

Thanks for your reply. I have already tried to reset the device to factory settings. The firmware version I have is M18QW_v07.05.170721 and when checking for updates, it says that there is no update available at this time. However the problem persists. One thing I have noted, if that helps, is that the mobile connection tends to drop from time to time. And the weird thing is that when it happens, I can still see typically 3 signal strength LEDs lit up on the device. So the connection shouldn't be down at that time, should it? Also, FYI, following those problems, I have added an external antenna now giving me RSRP around -80 to -105 and quality around 43 to 52 in 4G, depending on the weather. But that antenna did not improve stability in any way.

Do you have any other suggestion?

[Paulivil]

I seem to have similar problem with my unit. fw shows the same 170721 although it was just recently updated. There's 1-3mb data usage every night, which costs me an euro per day. DSL log shows no dropouts. Elisa provides both DSL and cellular connection for me here in Finland. I've left the settings mostly in default so it works as an router, auto connects except when roaming and has only one device a smart home hub attached. Has worked very well when the DSL was suffering actual dropouts so these went unnoticed. Hw version 08. I bought this second hand on eBay as netgear Lb2120-100pes and paid 132 EUR shipping included. I have to get some lite account so will lose 4G unless there is some solution. I even bought an external antenna.

[Cameron147]

---

@MyFedLoan wrote:
I seem to have similar problem with my unit. fw shows the same 170721 although it was just recently updated. There's 1-3mb data usage every night, which costs me an euro per day. DSL log shows no dropouts. Elisa provides both DSL and cellular connection for me here in Finland. I've left the settings mostly in default so it works as an router, auto connects except when roaming and has only one device a smart home hub attached. Has worked very well when the DSL was suffering actual dropouts so these went unnoticed. Hw version 08. I bought this second hand on eBay as netgear Lb2120-100pes and paid 132 EUR shipping included. I have to get some lite account so will lose 4G unless there is some solution. I even bought an external antenna.

---

The firmware version I have is M18QW_v07.05.170721 and when checking for updates, it says that there is no update available at this time. However the problem persists. One thing I have noted, if that helps, is that the mobile connection tends to drop from time to time. And the weird thing is that when it happens, I can still see typically 3 signal strength LEDs lit up on the device. So the connection shouldn't be down at that time, should it? Also, FYI, following those problems, I have added an external antenna now giving me RSRP around -80 to -105 and quality around 43 to 52 in 4G, depending on the weather.

[Paulivil]

The problem with unwanted kick in seems to have gone away by setting the modem in bridged mode. This meant chaining it up with a router to make the home automation hub to be accessible. Maybe if I'd left dhcp on I could've left the hardware as it was. With this setup one of the wireless access points gets internet also during DSL down time. And I can access the modem user interface without any cable pulling.

[blackeyes]

FYI, my modem has been in bridge mode in between a DSL modem and another router. And I still have the issue.

[Paulivil]

I don't know how to link to the message but it was pretty recent and said this about firmware versions:
The new firmware version:

For LB2120-100AUS, LB2120-100EUS and LB2120-100PES, firmware version is NTG9X07C_13.05.04.00

And for LB2120-100NAS, firmware version is NTG9X07C_12.09.05.29

LB2120 (all SKUs) release notes:
New Features and Enhancements:

Added Keepalive settings to prevent the device from losing data connection due to idle timeout
Updated AutoAPN database to version 01.20
Bug Fixes:

Fixed security issue

[Paulivil]

so if the application version listed matches the one on your modem and you have the keepalive setting available, the firmware should be the latest.

[chris12]

I'm having the same issue.  I received over 110 SMS alerts today where the LB2120 said it was failing over to LTE and then switching back.  The cable modem connection was fine all the time, though.  I rebooted the device and it has seemed ok for 30 minutes at least.

I'd prefer it if I didn't have to reboot the device as the LB2120 is supposed to be a network resiliance device so I would appreciate an update on what is casuing the issue for us and whether/when the software will be fixed.  I'm happy to try changing a setting as a temporary workaround.

Thanks, Chris

[Blanca_O]

Hi @chris12

May we please know the device SKU (e.g. LB2120-100NAS)? This can be checked on the box of the product or on the barcode label

Kindly check if you device has the latest firmware. Here's the firmware version per SKU: 

• LB2120-100AUS, LB2120-100EUS and LB2120-100PES : NTG9X07C_13.05.04.00
• LB2120-100NAS : NTG9X07C_12.09.05.29

Regards,
Blanca
Community Team

[Paulivil]

I seem to remember the mentioned "firmware versions" point to user interface application versions, so my conclusion is that if the application version checks out also the firmware is the latest. Either that or the firmware is at the initial 2017 version.

[JohnPeng]

Thanks for the report. We have been investigating the issue for a while. We may need your help to collect some logs and help us verify the fixes later. Would you like to help us on these?

Regards

[JohnPeng]

Hi Chris,

You can log in to WebUI to disable SMS notification for failover faeture as a workaround for now.

Sorry for the inconvenience.

Thanks

[chris12]

Happy to help in the short term. I will want to return (to amazon) before the end of the return period if it isn’t fixed though. I think i have until jan 31st