Today I purchased a SIM from an ISP here in Finland that supposedly is now offering 5G SA (Standalone) as a SIM only plan without having to also purchase their equipment.
The sales person informed me this is a 5G SA connection however when place the SIM in the RUTX 50 I don’t get a 5G only option and if I set the connection so be SA then it defaults to 4G LTE like my previous 5G NSA (Non Standalone) SIM from another ISP.
And the RUTX 50 software UI is also prompting something about MTU 1280 or 1500 on the new connection and I don’t know what this means exactly.
So I am thinking either this is not actually a 5G SA (Standalone) plan, I have wrong settings or perhaps the device requires an external antenna to actually get 5G only and 5G SA connnection. If anyone could offer some advice I would appreciate it.
Update: I was able to configure the connection to use 5G only by selection LTE bands that are not available so it’s now running in SA mode it seems but there is still no 5G only network type selection.
Is there some kind of configuration script I can run to get it to lock to 5G N78 and ignore all else or something like that?
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Hi @davyjones ,
Preferred network type is usually controlled by the operator or SIM card. Have you changed to 5G SA plan and kept the old SIM? It might be that you need to replace it for the preferred network type to be 5G SA.
However, if this device is stationary, you can select 5G NR-only mode by navigating to System → Troubleshoot, and in Modem debug section run this AT command:
AT+QNWPREFCFG= "mode_pref",NR5G
This change will likely be overwritten once the device is rebooted or mobile connection is re-established, thus I would also suggest placing this command in custom scripts:
gsmctl -A 'AT+QNWPREFCFG= "mode_pref",NR5G'
Best regards,
Hi, no it’s a completely new SIM as it’s from a different ISP. And yes the device is stationary. I will try those commands and report, thanks!!
I have added the custom script after I added the latest firmware.
Some how the device seems to be in an add MTU 1280, then MTU 1500, the MTU 1280 endless loop now.
I had these prompts after I first inserted the new ISP 5G SA SIM, I then set 1280 and then it prompted to add 1500 and the once the connection restarted the prompts disappeared. Now it seems to continue for some reason, odd.
Nevermind, the MTU endless loop appears to have calmed down now. Or at least it’s not presenting the MTU 1280 or 1500 messages anymore.
It’s now running at 5G SA based on these connection settings. I understand the point that the connection options will be based on what the operator provides but was the script suggestion supposed to offer a Preferred network type of 5G only?
Hello,
The script was offered as a suggestion to lock the device to 5G SA.
It could be that some sort of caching mechanism is now in place and the device will connect to SA network on it’s own. Could you try selecting 4G-only → Save and Apply → change to 5G/4G/3G auto → Change preferred network type to SA and check if the device connects to SA on it’s own?
Best regards,
Thanks, this was interesting. I tried it and the first time it did not switch to 5G SA on it’s own so I started to take screenshots to record the process but then I repeated the same process again and it did.
Random questions if I may ask.
Since the router can now be running in 5G SA mode even though the following is applied,
Preferred network type: 5G/4G/3G auto
does it technically mean that than it’s in 5G only mode and that is how 5G only in applied in this case.
And I came across another post on the forum here listing the following CLI command to check the operator’s MTU vs what has been applied in the router. Based on what I have applied below are these command results valid?
Network > WAN > WAN interfaces > mob1s1a1 > Advanced Settings > Override MTU: 1500
root@RUTX50:~# gsmctl -A at+qmtuinfo
+QMTUINFO: 1,1500,1280
Hello,
Generally it’s best to check MTU by just using the internet - if you don’t experience any strange issues with certain sites (for example, only Netflix is buffering constantly, while text-based sites are okay) and if everything is working - leave it on 1500. I would be surprised if a modern 5G SA network uses MTU of 1280, as I’ve only seen it on some older networks. Since SA is still relatively uncommon, it may be that the modem interprets operator advertised value incorrectly or RutOS parses it incorrectly (although I haven’t seen any similar reports of this).
Let me know if you experience any further issues!
Best regards,
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A MTU of 1280 bytes doesn’t seem to be uncommon, at least for IPv6:
root@lgr5g:~# gsmctl -A 'AT+QMTUINFO'
+QMTUINFO: 1,1500,-
+QMTUINFO: 2,1500,1280
I have also been discussing this on the forum of the ISP providing the 5G SA connection. And someone there noted the following which was interesting.
i have teltonika TRB500, so thing are not same. but i have 5g only option and i can also select NSA and SA. but i cannot select 4g/5g mixed, which i think is bad. i haven’t test elisa sim card on TRB500.
I have 5G SA running based on the following so all seems otherwise okay so long as I start with as you suggested above, switching to 4G only, then the 5G mixed mode+SA and then it will connect.
Preferred network type: 5G/4G/3G auto
5G mode: SA
Band selection: Auto
Network type: 5G (SA)
Bands: 5G N78
I was wondering though is a “5G only” option an actual option inside the router OS or does it render dynamically based on what the connection is telling the device or the method above that I have, i.e. 5G mixed mode+SA is techically the same as 5G only?
@davyjones ask that person which RUTOS version he have. Most possibly, it will be quite old, as previously this 5G only was available, but it was removed as it confuses users - when 5G only was selected, only SA mode could work, but some users didn’t know that ant expect 5G NSA mode which uses 4G too. That’s why 5G only was removed and 5G network mode selection was introduced.
Ah ok, thank you as this I did not know about
