TRB500 unstable connection


I have installed a TRB500 a couple of days ago and am having some issues. With the factory mobile configuration it keeps dropping the connection once or twice per minute, as in complete disconnect and no internet. Also 5G speeds are much slower than 4G for some reason (<200 Mbps for 5G, >300 for 4G) so I am forcing it to use 4G only. It drops both under heavy usage or no usage.
I found that B7 was very weak so I blacklisted it which improved things a lot, I now at least stay connected but looking at the mobile status page there’s still a lot of reconnecting going on and my speed drops to around 40ish Mbps during the reconnects.

I’m now trying to figure out what is causing it, it is quite annoying and I didn’t have this problem with my old router (D-Link DWR-978). I’ve kept an eye on the status page and am seeing a lot of fluctuation in RSRP, and I’m not sure if that is normal. Eg B20 in the attached screenshots jumps from -84 to -107? At the same time both B3 and B28 are dropped and sometimes (not always) a B8 shows up only to disappear again shortly after. I have tried disabling B8 but that did not fix anything.
I do not have low signal reconnect enabled.

My setup, I live in a rural area in northern Sweden, antennas are 2x LPDA-92 mounted on the roof at +45 and -45 degrees, connected to port 1/2. The antennas that came with the gateway on port 3/4.
The nearest tower is about 5 km away and there’s another one 10 km away in a more populated area, there’s about 5 degrees between them so my antennas are kind of pointing at both of the towers.
Only forest between me and the towers, open field for the first 50m from the house if it matters.
Firmware updated to the latest but that did not seem to help at all.

I should add I did not have any of these problems with my old router with just the 2 LPDA-92 antennas, it was rock solid and rarely ever lower than 350 Mbps, so I’m thinking it must be a configuration problem somewhere. I bought the TRB because it would allow me to use 4 antennas and have the gateway outside closer to the antennas so I can use shorter cables, basically I’m hoping for more speed with the TRB. I am hesitant to buy another 2 outdoor antennas now though, because so far with 2 antennas it has not been performing as well as the old setup, and I’m actually considering returning the TRB and going back to the old setup.

So my questions are, what could be causing the irregular signal strength and drops and what do I need to do to get a stable and fast connection?

Thanks in advance!

Any help here?

i have the same problem! and have tried everything…
Have asked for help to…
hope we can find a solution… the TRB500 is not cheap, so i think they should work better…

@indbyggeren I hope so! I saw your thread and it sounds like a similar issue. What is your antenna setup?
I am wondering if the disconnects are caused by the modem trying to switch between antennas or something in my case, going from outdoor to tiny indoor antennas could maybe explain such a drastic jump in signal strength and connection loss.
I have tried moving the outdoor antennas around to different ports but that did not improve anything, and when moving them to 3/4 even made it much worse.


i have an standard 4/5G antenna with to cables/two connection. it is mounted om a pole outside and pointed direct at the mast.

I have now today set the modem/TRB500 to 3G/4G/AUTO. so it will not try to connect til 5G.
ANd it seams tha it have done the trick regarding the unstable mobile connection.
It has been stable the whole day.
So my conclusion is that there is something wrong with the 5G in the modem software…
i dont understand why Teltonika have not corrected the problem as i can se that many Others have the same problem. and not only with the TRB500 but also with other 5G products.

What is device and modem FW versions?

Firmware version
Firmware build date
2024-04-15 11:34:58
Internal modem firmware version
Kernel version

My firmware info:

  • Firmware version TRB500_R_00.07.07
  • Firmware build date 2024-04-15 13:34:58
  • Internal modem firmware version RG501QEUAAR12A09M4G_04.200.00.000
  • Kernel version 4.14.336

@indbyggeren which ports have you connected your antenna to? And do you have anything connected to the other 2 ports?

outdoor antenna on port 1-2
standard antenna on port 3-4

09h 59m 22s
without fails…

Read older posts or type TRB500 into the search form, you will see that there are quite a few problems with the modem in this device.

As for the antennas, do not combine the external and internal antennas, because the signal is measured incorrectly, the external antennas have a higher gain and the internal antennas have a weak gain and the modem gets confused in measuring the signal, either leave only two external antennas connected or connect all four antennas, either external or internal (omnics).

It is important to test on which SMA ports the modem works correctly with two antennas, on my RUTX50 it is the first two SMA ports on the left.

With external antennas, you must pay attention to the distance between the antennas, for example, to amplify band B3, the distance should be 34 cm.
I use Iskra P-60 MIMO external antennas, probably the same applies to your antennas.

Next, Quectel modems seem to have a bug in signal measurement when they work with only two antennas (and the base in SISO mode) and I reported it to Quectel, but it may take months to fix it

@tirkiz thank you for your insight!

I’ve tested leaving the 2 internal antennas off but it seemed to get even more confused by that, but I will test again. I’m pretty sure it’s the 2 left most ports on the TRB500 as well, when I connected them to the 2 right most ports and nothing to the left it would not connect at all.

I use Poyntings ±45 bracket for the antennas, I think it spaces them less than 30 cm apart, so that may be worth experimenting with.

But I guess it is safe to say then that getting 2 more external antennas will circumvent this bug and most likely fix my issue. If not maybe I can interest one of my neighbors in 2 antennas… Just hope it will also give me better performance and stability than 2 antennas and a modem without this bug :slight_smile:

It should work ok with only two antennas, it is important to guess which are the exact SMA ports for working with two antennas.

When trying which SMA combinations work best, you have to reboot your router every time and see if the internet works. If the internet is working, you need to monitor it for a few hours or a whole day to see if it is stable or if there are strange outages, interruptions, etc. So that requires patience.

Make sure that the external antennas are pointed precisely towards the base station (tower).

The better the signal (RSRP, RSRQ, RSSI and SINR), the better the connection stability and speed.

If you buy two more antennas, you have to be careful how to mount them, because then you have a 4x4 MIMO configuration.
In the link below you have my 3D picture of how to mount 4 external antennas, there must also be a proper distance, for example 34 cm between each to amplify primarily the B3 band.

If none of this improves the signal, you can always sell external antennas.

How far is the base station (tower) from you and can you see it or are there any obstacles?

If you have more base stations (towers) in range, you can turn the current external antennas towards another base station and test the signal and speeds :slight_smile:

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