RUTX50 intermittent loss of IPv4 connectivity on Telia FI network

Networking Solutions Issue
1

Hello,

I am experiencing intermittent connectivity issues with a Teltonika RUTX50.

Device:

- RUTX50

- Firmware: RUTX_R_00.07.24.1

- Operator: Telia Finland (24491)

- Network mode: 5G NSA

- External MIMO antenna connected

Issue:

Several times per day internet connectivity is lost for approximately 1-5 minutes.

During the outage:

- Health Checker reports “IPv4 connectivity started to fail”

- Later “DNS resolution started to fail”

- Both are restored automatically after a few minutes

- Direct ping to 8.8.8.8 also fails during the outage, so the issue is not limited to DNS resolution

Example:

2026-08-07 13:15:30 IPv4 connectivity started to fail

2026-08-07 13:17:03 DNS resolution started to fail

2026-08-07 13:19:33 IPv4 connectivity restored

2026-08-07 13:19:36 DNS resolution restored

Another example:

2026-08-07 05:57:04 IPv4 connectivity started to fail

2026-08-07 05:59:19 IPv4 connectivity restored

I also observed the following during one outage:

Request timeout for icmp_seq 116

Request timeout for icmp_seq 117

Request timeout for icmp_seq 118

Request timeout for icmp_seq 119

Request timeout for icmp_seq 120

Request timeout for icmp_seq 121

Request timeout for icmp_seq 122

Request timeout for icmp_seq 123

Request timeout for icmp_seq 124

64 bytes from 8.8.8.8: icmp_seq=125 ttl=117 time=520 ms

64 bytes from 8.8.8.8: icmp_seq=126 ttl=117 time=29 ms

Interesting observations:

- Signal quality is good.

- Typical latency is around 18-30 ms.

- Upload performance is very good.

- The modem does not appear to disconnect from the cellular network during these events.

- I do not see “Mobile data disconnected” or network re-registration events corresponding to these outages.

- WAN lease renewals appear normal.

- Upgrading from RUTX_R_00.07.23.7 to RUTX_R_00.07.24.1 did not solve the issue.

System log also contains:

dnsmasq: Maximum number of concurrent DNS queries reached (max: 150)

I am not sure whether this is a consequence of the connectivity outage or a possible root cause.

Additional information:

The same Telia SIM card and the same external antenna setup were previously used with a TP-Link Deco X50-5G, where I did not observe similar connectivity interruptions.

Has anyone seen similar behaviour on RUTX50, RUTOS 7.24.1, or the Quectel RG50X modem?

Could this be related to:

- PDP session handling

- RUTOS

- Quectel modem firmware

- Telia Finland network compatibility

- DNS issues

- something else?

I can provide additional logs if needed.

Thank you.

2

Ok, another one connectivity loss. This time I even could not load status/Mobile page:

kuva
kuva602×245 13.9 KB

3

Flash your device from boot loader mode in order to fix this issues. First download firmware for your device from here, and then follow these instructions on how to flash. Before you say “my device is already on version 07.24.1 why should i flash again?” That doesnt matter at all. Flashing same firmware from boot loader mode is different than upgrading from web ui. Its a known way of solving many, if not all issues on this device.

4

Thanks, Heartless.

I gave it a try and reflashed the router from bootloader mode. I didn’t restore from backup anything.

Let’s see if it makes a difference.

Appreciate the help.

5

Just let us know if it solved the issue or not. Im recommending this method to everyone that has this device and similar problems, and it seems to solve all issues every single time.

6

Well, uptime was about 1 day and 11 hours since that reflash and then I noticed that Internet connection was down.

teltonika1
teltonika11652×1137 115 KB

Here is event log filtered by “ipv4”. That last one disconnect I had to manually restart since it has not recovered by itself after about 15 minutes.

teltonika2
teltonika2796×305 27.6 KB

Curiously, modem connection seems to be active while Internet connection is down. It has been every time I checked.

7

Here is your problem right there. You have VoLTE enabled. Disable it. Also, if your provider is not relying strictly on IPv6, disable that as well.

8

Thanks, Heartless.

I have now disabled VoLTE and also switched the PDP type from IPv4/IPv6 to IPv4 only.

For reference, VoLTE was set to Auto in the default configuration after the bootloader reflash and setup wizard.

You seem to know these devices quite well, so I appreciate the suggestions. I’ll keep testing for a few more days and report back with the results.

9

Another update.

I am still seeing IPv4 connectivity outages.

The most recent outage took approximately 7 minutes to recover by itself:

2026-08-13 09:00:54 IPv4 connectivity started to fail

2026-08-13 09:07:40 IPv4 connectivity restored

2026-08-13 09:07:43 DNS resolution restored

I have also observed at least one previous outage that did not recover within approximately 15 minutes, and I had to manually reconnect the mobile data connection.

At the moment I have:

- reflashed the device from bootloader mode

- configured it from scratch

- disabled VoLTE

- changed PDP type from IPv4/IPv6 to IPv4

- tested 5G SA (not available in my area)

- started testing LTE-only mode

One interesting observation is that the modem still appears to be connected and registered to the cellular network while the Internet connection is unavailable.

Since the issue persists even after a clean bootloader reflash and reconfiguration, I would appreciate it if Teltonika support could review this case and advise whether additional diagnostics or a support ticket would be appropriate.

Thank you.

10

This could be the problem on mobile provider side. Is there any chance you can test another SIM card/provider? Also, what are the signal levels and are your antenna screws properly tighten?

11

Thanks for the suggestions.

I may be able to test with another operator SIM card. I have access to an Elisa SIM that I can temporarily try in the router, so I’ll keep that as a possible next troubleshooting step.

Regarding the antenna installation, the antenna connectors are properly tightened. I also don’t strongly suspect the antenna setup itself because I have seen very good performance at times, including low latency and excellent upload speeds. Current LTE signal levels look reasonably good as well. I do have Iskra P-60 MIMO antenna connected to the router’s Mobile0 and Mobile3 antenna ports, as recommended by the reseller.

I have now been running in LTE-only mode for almost 23 hours. During that period I have observed only a single outage:

09:47:26 IPv4 connectivity started to fail

09:48:00 Mobile data disconnected

09:48:16 Joined LTE network

09:48:19 Mobile data connected

09:48:29 IPv4 connectivity restored

After that event the connection has remained stable for nearly 23 hours.

I’ll continue testing LTE-only mode and report back if the issue reappears.

12

I have observed this issue for quite some time and by default have disabled the Internet Status feature under network due to the onslaught of Event Logs it creates.

13

You have to keep in mind that some providers kick clients from their network after some time. So take that into consideration when troubleshooting.

14

A small update.

Regarding the Internet Status feature, I did try disabling it earlier. The IPv4/DNS warnings disappeared from the logs as expected, but I still experienced actual connectivity outages. In practice that only made troubleshooting harder because I lost visibility of when the interruptions occurred.

As for the LTE-only test, the results are interesting so far. Apart from a single outage shortly after switching modes, the connection then remained stable for almost two days without any further IPv4 connectivity failures.

Because of that, I am starting to wonder whether 5G operation may somehow be involved. Whether that would be a network-side issue, a modem issue or a firmware issue, I don’t know at this point.

I have now obtained an Elisa SIM card and started testing with a different operator using the same router, location and external antenna setup. I’ll let it run for a while and report back with the results.

Hopefully someone from Teltonika support can also take a look at this case, as it would be interesting to know whether this behaviour is familiar to them.

15

Another update.

I have now been testing with an Elisa SIM card using the same router, same location and the same external antenna setup.

So far I have not observed any new IPv4 connectivity failures, DNS failures or unexpected mobile data disconnects with Elisa. The connection has now been stable for roughly two days.

For reference, I have:

- upgraded from 07.23.7 to 07.24.1

- reflashed the router from bootloader mode

- configured it from scratch

- disabled VoLTE

- changed PDP type to IPv4 only

- tested Telia in LTE-only mode

- tested with a different operator (Elisa)

What I have seen so far:

- Telia 5G NSA: repeated IPv4 connectivity failures

- Telia LTE-only: stable after one observed outage

- Elisa 5G NSA: stable for approximately two days

At this point I am wondering whether this could be related to Telia’s 5G NSA network, a compatibility issue between Telia and the RG50X modem, or a firmware issue that only appears with a specific network configuration.

Has anyone seen similar behaviour before, or could someone from Teltonika support comment on this?

16

Its possible that Telia has a specific configuration for that location/cell tower.

Thats not possible because modems are standardized. Its all about configuration or misconfiguration at providers end. And those things are out of your control. You had no issues since you switched to Elisa and that pretty much tells you everything you need to know.

Mobile providers can implement rules at their end that get triggered when non mobile phone device connects to the tower, or a router/brand that was not supplied by them. Some providers in my country do exactly that. You get a full internet speed on your phone and device they supplied, and poor speeds on the router of your choice. Device can get identified based in their IMEI or MAC address, and these parameters can trigger different rules. Some providers do this, some dont. This is why you need to be very careful when testing. Especially if your are comparing your Teltonika device to another brand. Your Nokia or TP-Link may work flawlessly with Telia, but cause issues with Teltonika.

I had exactly the same issue with the provider i used long time ago. They kick my router off their network every two hours every single day. I called them and asked them about this, and they just blatantly told me that this is how their tower is configured in that area because of high car traffic. Switched to another provider, no issues since then.

17

Another update.

I have now completed almost 7 days of testing with an Elisa SIM card using the same router, same location and the same external antenna setup.

During that period I observed two IPv4 connectivity failures:

2026-08-18 14:17:32 → 14:18:35

2026-08-20 23:24:44 → 23:25:47

Both lasted approximately one minute.

So Elisa was not completely free from the issue, but the behaviour was significantly better than with Telia 5G NSA. With Telia I experienced more frequent interruptions, DNS failures and some outages lasting several minutes. Signal levels with Elisa were also generally worse than with Telia.

I have also found the performance differences between devices interesting. Using the same Elisa SIM card in an old Samsung Galaxy Note 8 (which does not support 5G), I measured download speeds close to 150 Mbps over 4G. I have also previously seen higher speeds with a TP-Link Deco X50-5G (using the original Telia Finland SIM card) than with the RUTX50, even when the Deco was using only its internal antennas indoors.

I have submitted a fault report to Telia and provided a link to this discussion. I am also curious whether Telia applies any device-specific policies or network configuration differences that could explain the observed behaviour.

I will now switch back to Telia and continue testing under the same conditions.

18

I also found the following messages in the kernel log:

qmi_wwan 2-1:1.4 wwan0: NETDEV WATCHDOG: transmit queue 0 timed out

(repeated multiple times)

Since qmi_wwan appears to be related to the modem interface, could these messages be related to the IPv4 connectivity failures I have been observing?

19

Small update.

Following feedback from Telia, I noticed that the router was configured with 5G mode set to Auto. According to Telia, the modem had occasionally attempted to use 5G SA, which is not yet generally available in their network.

I changed the setting to NSA-only and continued testing.

Unfortunately, IPv4 connectivity failures still occur, so the issue was not completely resolved by forcing NSA mode. Recent examples:

2026-08-28 03:57:33 → 03:58:36

2026-08-30 04:03:08 → 04:04:11

2026-08-30 10:31:39 → 10:32:42

2026-08-30 13:11:43 → 13:13:59

2026-08-30 23:08:15 → 23:11:43

On the other hand, the behaviour still seems less severe than during my initial testing. I am continuing to monitor the connection and compare the results with the previous Elisa test.

20

Another update.

Based on feedback from Telia, I changed the 5G mode from Auto to NSA-only. According to their analysis, the modem had occasionally attempted to use 5G SA, which is not yet generally available in their network.

Unfortunately, forcing NSA-only did not resolve the issue.

Since making that change, I have continued to observe IPv4 connectivity failures, and DNS resolution failures have also reappeared. Recent examples include:

2026-08-31 16:33 → 16:34 (IPv4 + DNS)

2026-08-31 22:26 → 22:30 (IPv4 + DNS)

2026-09-01 00:43 → 00:46 (IPv4 + DNS)

2026-09-01 17:47 → 17:55

2026-09-02 18:49 → 18:50

2026-09-02 23:56 → 00:00 (IPv4 + DNS)

2026-09-03 00:11 → 00:12

2026-09-03 01:33 → 01:34

One interesting observation is that these failures are generally not accompanied by “Mobile data disconnected” or a network re-registration. The modem appears to remain attached to the network while connectivity temporarily stops working.

A new firmware version (07.24.3) has become available, but I have not installed it yet.

I have also opened a new fault report with Telia and provided them with updated information.