@Vilius, please don’t take me wrong, but I must say I found your answer not addressing any of the concerns @gt-solutions expressed. Further, is it the official Teltonika advice to follow the guidelines posted by an external party on GitHub? I cannot think so.
If those instructions are correct, why not post those instructions yourself (i.e. Teltonika)?
I don’t know how many threads I’ve seen with questions about the modem firmware version and how it can be updated. A forum search for “modem firmware”, today, gives 358 results.
Obviously, I haven’t read all of them, but I remember seeing seemingly conflicting messages from Teltonika moderators. Often with the reponse to stay clear of updating if there’s no clear issue, and that incorrect updating can damage the device (see, for instance, the response by Justinas on 21 November 2025 in TRB501 modem firmware update - #5 by Justinas ). @Vidas.K gave quite informative answes on the “how to” question.
The above mostly covers the “how to” … but questions regarding modem firmware version releases is mostly unanswered. Please prove me wrong.
I would recommend that Teltonika clearly communicates the policy on modem firmware releases, information on how to get and install the update, etc … and then refer to that in posts about modem firmware updating.