RUTX12 poor performance on primary modem only

Hello fellow Teltonika enthousiasts,
the primary modem on my RUTX12 seems to be struggling to provide a stable and fast connection :frowning:

Websites often timeout and performance is always worse compared to when I use the secondary modem. In terms of performance on the primary modem, there are fluctuations. My last test was doing 4Mbps down and 100kbps up, but I have also seen 2Mbps down and 15kbps up. The best performance so far was 6Mbps down and 2Mbps up. After each test, I immediately did the same speedtest using the secondary modem and was always greeted with speeds of around 15Mbps down and 11Mbps up. Switching back to the primary modem resulted in slow speeds again (and sometimes not being able to browse or ping at all, despite the device indicating it had an active data connection).

I am using CloudFlare’s speedtest and am making sure that the network is idle during the tests. I am using only 1 sim card and have been swapping it between both modems to troubleshoot. Both negotiate on 4G and have 2 out of 3 signal quality LEDs. The RUTX12 is sitting on my desk and has all 4 mobile antennas connected and pointing in the same manner into the same direction. Have tried swapping the antennas but the problem remains on the primary modem.

I’m not sure what firmware I started with, but I updated to firmware 07.06.3 and later to 07.06.5. The primary modem was on firmware EG06ELAR04A04M4G while the secondary was on A07. I’ve updated both modems to A20 (going through the mandatory A07 and A08 intermediate versions) but the behavior remains the same.

I’m starting to think I might have a faulty unit. Does anyone recognize this issue? Is there any useful diagnostic I can run to further pinpoint the problem? Any pointers are much appreciated.

Best regards,


It seems like there might be an issue with the modem. To confirm, please try using a different SIM card and check the settings for SIM 1. Ensure that the correct network type or band is selected.

If this doesn’t resolve the issue, you can perform a factory reset (remember to backup your data first) to confirm if the problem lies with the modem.

If none of these solutions work, kindly reach out to your Teltonika device supplier to initiate a Return Merchandise Authorization.

Best regards,


This topic was automatically closed after 15 days. New replies are no longer allowed.