Dear Forum,
I would like to share my problems using a RUTC50 router with a (Dutch) KPN 5G SIM card.
The data connection runs very well for most things, getting 400+ Mbps downloads and 70+ Mbps upload speeds.
As soon as video streaming (youtube) gets into play I can see trouble occurring. Videos are often almost impossible to watch due to playback hiccups. Using the “stats for nerds” build into Youtube you can see the connection speed dropping en raising all time as sometimes exhausting the read-ahead buffer, causing hiccups.
Although my Antenna setup still needs improvement I have the feeling this is not the real cause of the problems. The router lives on a polyester boat.
Using the same 5G SIM in a Acer Connect Enduro M3 (5G) router works fine. Using the Teltonika router with an (expensive) Starlink antenna/connection works fine as well.
After having a phone call with Teltonika support I got the suggestion to force the router to select specific 5G/ LTE/ UMTS bands instead of the router doing automatic selections.
So I selected the best receiving bands. This seems to improve the situation considerable but still not as what it should be. Although it is usable as a workaround, it is not a great solution as moving the boat would force me to change the bands every time.
So my question is if anyone else has had similar problems and if there is permanent fix for this problem. I will improve on my antenna setup in the near future but this is not a trivial thing to do on a boat that already has crazy amount of cables running in all directions.
Kind regards,
Arno Luijten,
SV Luna
Rotterdam, The Netherlands
Majority of issues with unstable speeds and modem disconnects are caused by bad/low signal or congested cell tower. You may get super high speeds on speed test and think, ok speeds are good, everything should work fine. But then, you play the stream, and 15 minutes later your stream becomes choppy, pixelated or just stops. This is a timing issue. Cell towers are not always congested. With external antenna you can improve signal and modem stability, but nothing can save you from 3000 people connected to same tower that watch youtube and tiktok videos.
Thank for your reply. I have some more information that makes the problem even less understandable:
When running Youtube in a browser on a Macbook Pro M1 I get excellent speeds with no delays whatsoever. At the same time on the App either on a iPhone, iPad or Apple TV the problems are very visible.
Cheers,
Arno
Just tested it with a Windows laptop as well. Speeds are great as well. So the browser version seems to do things different from the app version, causing the app version to fight the connection.
That narrows it down to WiFi issue. You probably have to change your WiFi channel, or check if your WiFi antennas are properly attached. Make sure they are screwed tight. Install WiFi analyzer tool on your phone, and scan your WiFi surroundings. Find the channel that is not occupied and set that in your Teltonika device.
YouToube is constantly performing so called A-B testing on regions and devices. Especially if you are not paying for premium and you are using VPN, adblockers, trackerblockers…etc. YouToube is deliberately throttling your YouTube traffic and it makes is very difficult to use unless you give them money. So keep that in mind when testing.
Greetings, @aluijten,
Welcome to Teltonika Community!
After reviewing your description, it appears that the issue is likely related to the application itself. However, from the device side, as a last troubleshooting step, you may try adjusting the MTU settings on the mobile WAN interface.
MTU controls packet size and is typically set to 1500 by default. For testing purposes, you can try lowering it to values such as 1460, 1420, or 1380 and observe whether this has any impact on performance. To modify this setting, navigate to Network → WAN, edit the mob1s1a1 interface, open Advanced settings, and adjust the Override MTU value as shown in the screenshot.
Additionally, if you are using YouTube Premium, it may be worth contacting YouTube support directly regarding the application behavior. Based on your description during the call - where general internet access, file downloads, browsing, and video playback via a web browser work without issues - the problem appears to be isolated to the YouTube application rather than the network connection itself.
I hope this helps clarify the situation.
Warm regards,
V.
Hi Heartless, that would make sense only why is the problem not occurring with the Acer router and if I use the Starlink connection.
I wonder if the 5G provider plays a role in this problem
That narrows it down to WiFi issue
That seems unlikely as all devices are connected using the same WiFi network
Cheers, Arno
Hi I did lower the MTU, very little if any result.
So I played a identical video almost at the same time with the laptop and the iPad with Stats for Nerds active. Both are connected to the 5GHz WiFi network on the RUTC50.
Laptop
iPad
The speed difference is crazy between 170 and 300 Kbps for the iPad and more then 65000 Kbps for the laptop.
I can’t understand why this is.
So when I run Youtube in the safari browser on my iPad, the speed is similar to the laptop. Again there is something funny with the Youtube app…
Arno
Dear Support,
I kindly ask you to try to investigate the difference between streaming via the YouTube app and YouTube in a browser. I have been trying numerous things now to no avail. I guess you have more sophisticated stuff to analyse network traffic.
I still do not understand why a “simple” Acer Enduro M3 portable router can use the same SIM with no problems at all and why the RUTC50 is struggling on this streaming stuff so badly. I’m also using a Canal+ streaming app (sort of Netflix) and that seems to have problems as well, although not as bad as the YouTube App.
Thanks in advance,
Arno Luijten
Greetings,
Thank you for your message.
Since the connection behaves normally when using a different internet source (Starlink, in your case), this suggests that the issue is likely related either to the mobile network provider or to the YouTube application itself. If possible, I would recommend testing with a SIM card from a different provider to check whether there are any noticeable changes in performance. Additionally, you can reach out to youtube customer support if the issue is application related.
From the device perspective, the only available adjustment to test is modifying the MTU value. MTU defines the packet size used on the mobile connection, and in some cases, a mismatch between packet size and application handling may result in issues such as stuttering or buffering. Adjusting the MTU may help determine whether this is contributing to the behavior.
Kind regards,
V.
Hi Vilius,
Thanks for your quick reply.
My problem is why does the SIM behave without a problem when used in a Acer mobile router? Also I’m using the same provider on my iPhone (using an e-SIM) and when that is using 5G the YT app works fine as well. And on my phone I cannot set the MTU as far as I’m aware.
To me it seems the modem of the RUTC50 is doing something problematic when streaming. I saw some other posts on this as well for Teltonika 5G routers.
I have a Vodaphone SIM in my car, so I can try that. But that runs a very limited contract as it’s only for traffic information.
Kind regards,
Arno Luijten
Hi Vilius,
I managed to test the system with a Vodafone NL SIM.
This “solves” the problem. The signal strength seems a bit lower overall but the apps are working as they should. See below.
So that leaves me with the following situation
- KPN SIM in Teltonika gives problems when using streaming apps. HTML streaming goes well MTU changes do not help.
- The same KPN SIM in Acer Enduro M3 works fine.
- KPN eSIM in iPhone works fine for streaming apps
- Vodafone SIM in Teltonika works fine overall.
To me it seems there is some conflict between the KPN network and the Teltonika modem software using specific data-transmission protocols involving app-streaming.
I have no means to dig any deeper than this so I need Teltonika to investigate. Of course I will be happy to help.
As I just entered a contract with KPN for this SIM I’m tied for a year to this SIM.
Kind regards,
Arno Luijten
Hi Vilius,
Can you please let me know how to progress this issue. It is really annoying.
Kind regards,
Arno Luijten
Greetings,
I hope this message finds you well.
I have forwarded this case to our R&D team for further investigation. I will keep you informed as soon as I receive any updates from them.
In the meantime, your patience is greatly appreciated.
Kind regards,
V.
Greetings,
I hope this message finds you well,
After consulting the R&D team they gave me some suggestions that you might try:
- Set custom DNS of 1.1.1.1 and 8.8.8.8 on mobile interface (DNS servers pushed by the operator might be causing issues).
- Lower the MTU on the mobile interface. Try 1400, 1300, etc.
- Try blocking QUIC protocol (firewall rule to block outgoing UDP traffic on port 443).
- Double-check and ensure that SIM gets only IPv4 (you can try setting PDP type to IPv4).
Please let me know how it goes,
Warm regards,
V.
Hi Vilius,
Thanks for your quick turnaround with the R&D suggestions.
Point 1 and 2 were already implemented by me, with no result.
Point 3 is unclear to me for what I need to setup for this.
Point 4 was something I looked into before but was not able to tackle in full. Thanks to your hint about the PDP I was able to set it correctly.
It seems the problem is now no longer there. IPv6 seems to conflict between the modem and the KPN provider. I don’t know what the need would be for IPv6 so I’m happy to keep it switched off.
I will do some more testing the coming days but the early signs are promising.
Kind regards,
Arno Luijten
Greetings, @aluijten,
Thank you for your swift response,
Regarding point 3, this refers to Network → Firewall → Traffic Rules, where you can create a rule to block all outgoing UDP traffic on port 443. Make sure to apply the rule and test the behavior to confirm it works as expected.
Additionally, please keep me updated on the results of your testing so we can verify if the configuration meets your requirements or if any further adjustments are needed.
I look forward to your reply,
Kind regards,
V.
