Troubleshooting LTE keeps disconnecting
This Article Applies to:
All 4G LTE Routers
Issue Description/Phenomenon:
Some customers might experience interruptions or disconnections with their 4G LTE routers, their phones or laptops can connect to the router wireless network fine, while they display a 'No internet' error, and customers cannot access the internet. This article aims to provide suggestions on the issue.
Troubleshooting Suggestions:
1. When it loses the internet access, please check if you can still login to the router web GUI, then show us the Internet Status, SIM Card Status as follows. Compare the Network Type and Band, if they are the same as those when the internet is working fine:
2. If the band was changing to a different one when the internet interrupts, please follow the guide below to manually select a band that works in your network
How to select 4G band manually on the web interface of LTE Gateway Routers
If your LTE router doesn't support manual band selection, you could get the beta firmware from this thread:
https://community.tp-link.com/en/home/forum/topic/241534
3. If the problem still exists, please insert the same SIM into another LTE device or even a smartphone, then monitor for some time to confirm if the internet works fine and is stable.
4. If the 4G signal in your area is strong and stable, please try to change the Network Type on Advanced->Network->Internet page from 4G Preferred to 4G Only to see if it would be more stable.
If the issue is not located or resolved, please comment below on this topic and be sure to provide the following information:
- Model no. , hardware, and firmware version of your TP-Link device
- Working mode of the router, like 3G/4G router mode or wireless router mode
- Where are you based, and who is your SIM card carrier?
- Screenshots of Advanced->Status page and Advanced->Network->Internet page when the internet works fine and also when the internet stops
- System Log file without rebooting the router
- How often does the problem happen, and how does it recover?
- When did you purchase the router, and when did the issue start to happen?
- Is the same SIM card working fine and stable on other 4G devices?
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Some joy here: 7 days with ZERO drops since using the HPM 12 outlet RFI filtered powerboard. It probably does EMI as well. I’m still using an upgraded wall adapter which has some filtering on the cord.
TP-LINK 4g modem/router dropping LTE internet connection solution for me is RMI / EMI filtering.
Big thanks to Courtney from ONE nz for her help.
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TL-MR3420 with Huawei E3372, 4G, Estonia
Periodic disconnection from 4G itself is not a big problem. Big problem is that after loosing 4G connection, it is never recovered. TL-MR3420 web interface shows, that 4G is disconnected and all buttons are inactive. E3372 led shows, that is has stable 4G connection. Only way to reconnect 4G is disconnecting/reconnecting 4G modem fom USB or power reset of TL-MR3420 modem. The situation is actually worse. In 10-20% of cases after power reset (or just switching on the router) we have the same situation - modem shows stable 4G but is not connected to router. Restoring internet connection needs human intervention.
Our system is servicing devices, where humans are not always present. So I used a "workaround" as external resetting TL-MR3420 power every 6 hours. Well, sometimes the internet connection was not established after restart, but usually next restart was successful and I had internet just paused by 6 hours. Anyway it was better than every time drive over 100km to just reset modem.
Finally I found device named "Keep Connect Router Rebooter", which does what needed: it is monitoring over WiFi internet connection and when it is lost, does power reset of router (3 attempts, configurable). If there is still no connection, it repeats these attempts every 4 hours (configurable) until connection is restored.
So, for me the problem seems to be solved (externally), but I have a proposal. Algorithm, described above (OK, in fact it is a bit more complicated), could be be realized on the router level. That means, why not to add option: "Hold/restore 4G connection", where in case of loosing 4G connection, USB connection with 4G modem is restarted 2-3 times, and if no success, repeated every 3-4 hours. Or, instead of just restart USB, reset whole modem, which will restart everything.
Right now, if 4G is once lost, there are no attempts at all to recover this connection.
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Hi, thank you very much for the feedback.
May I know the hardware and firmware version of your MR3420? and what is the exact model of your E3372 USB modem? as far as we know, E3372 might have different products such as E3372h-320, E3372h-607 etc..
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Exactly this! I just ordered Shelly Plug Plus S that I will script to hard boot the tp-link modem when the connection is lost.
It is unbelievable that these devices can't reconnect when the connection is lost. This should be very basic operation for a modem. The modem knows that the connection is lost but it still can't reconnect and nightly boots do not usually help. I have to unplug the modem to get it online again. I have NX510v 5g modem that is using 4g+5g, so things do not get better with tp-link 5g modems either.
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Hi! Right now I am away from the router but in couple of days I will be able to give more precise answer.
I have MR3420 v5. Firmware I do not remember, but latest available by september 2023.
I have tried this MR3420 with three diferent USB modems: plain E3372 with software of our ISP Elisa, E3372h-320 (it is connected right now) and E3372-325 (without h in name).
E3372 is oldest and works without problems with three different MR3420 v5 I have with original (not updated) firmware.
E3372h-320 initially did not want to connect to 4G (only 3G worked), but after MR3420 firmware upgrade (somewhere in june 2023) started working.
E3372-325 did not connect to 4G even with upgraded (in june 2023) MR3420 firmware. Did not check yet with latest one but try to do it soon.
Also small addition to my previous post. The modem connects to the relatively weak 4G quite a long time. Therefore when network type was set to "Automatic", then during startup in 50% of cases MR3420 gives up (shows USB disconnected) earlyer than modem was able to establish connection to G4. When I changed network type to G4, it improved situation - success in 85% and failure in 15% of cases. In case of failure helps only manual reconnect of USB or restart of router.
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Good luck with programming!
Agree, that periodic checking of internet connection and if necessary, resetting/reinitializing USB connection to the modem should be not too difficult. But from the other hand, external rebooter has one advantage, which is a bit harder to implement on the router side. Because this rebooter is connecting to the router over WiFi, it checks also if WiFi is working and restarts router when WiFi is lost. Checking WiFi from the router side is not so easy. OK, presence of connected WiFi devices can be monitored on the router side, but there can be devices that connect to WiFi just periodically. As example, Shelly H&T, which connects to WiFi every 10 minutes, reports humidity an temperature and disconnects. If there are only such devices, most of time there will be silence in Wifi and no connected devices. In this case, to avoid unnecessary reboots, there should be then configured some longer delay "without dvices" to wait, if some WiFi device will appear. Or some "anchor" device, which is constantly connected to the router, showing, that WiFi is OK.
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It's crazy that this is still an issue. It is almost exactly 12 months since I got an Huawei B818-263 4G router, and it has been almost flawless throughout that time. I use a TP-Link Mesh, and have had very brief connection drops. I think I've reset the router twice, perhaps three times, along with the entire mesh. The TP-Link router is an expensive ornament in my 'box of bits'.
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Thanks!
Actually the wifi has never been a problem on my system. I'm currently using Ubiquiti router, switches + AP's and these have been really reliable. My TP-Link Modem is only acting as a modem, so it should not have too much to do. This connection is used to monitor and control our second home heating (150km away) so it is quite crucial. I have to figure out something to make the connection last. Now it is dropping the connections almost everyday. After power cycle I get really nice 160Mbps connection, but I'm not interested in driving there everyday :D
Winter is coming!! Greetings from Finland :)
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Exactly my case, only the distance is shorter - 100 km Initially I used Huawei e5576-32 mobile WiFi. It has battery inside, so it survives power breaks and lost G4 only a couple of times during last winter. Unfortunately in this case only hard reset with reboot restored connection. Also it has quite weak WiFi signal which caused WiFi connection problems with Shelly thermometers. Therefore this summer I replaced this one by MR3420 with E3372. No WifFi problems at all, but once during a month or two it is loosing G4. Winter in Estonia is almost the same as in South-Finland :) so I had to prepare something, that will restore lost G4 connection without my intervence. And I hope that right now I have solution. Wiil see :)
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Hi! Finally I can send you exact versions of hardware and firmware.
Router:
Firmware Version: 1.8.0 0.9.1 v0001.0 Build 211220 Rel.70276n
Hardware Version: TL-MR3420 v5 00000002
G3/G4 modem:
Device name E3372h-320
Hardware version CL4E3372HM
Software version 11.0.1.1(H697SP1C983)
Web UI version WEBUI 11.0.1.1(W13SP1C7110)
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