Hello! First post here, and really impressed by Teltonika so far!
I have a RUTM51 router (7.21.3 firmware) which I’m using in Passthrough mode as a backup to a fiber connection. I have a Three UK SIM card in SIM1 (I am in the UK). I have turned off Auto APN and set APN as “3internet”.
The RUTM51’s connection appears to be working but because it’s in passthrough mode it’s a hassle to access its web page. I was hoping I could visually check connectivity on the LEDs, but the SIM1 LED is off, and the 3G/4G/5G LEDs are flashing in sequence. According to the docs that means the router is establishing a connection; but I know it’s connected because i’ve tested it in failover.
Does anyone know a situation where the connection would be made (albeit weak signal where I am), but the router still be flashing LEDs to suggest it’s not connected?
The SIM1 LED being off means a mobile data connection on SIM1 is not active as the router’s own WAN interface - which makes sense in Passthrough mode, since the router is handing the mobile IP directly to your downstream device rather than terminating the connection itself.
The 3G/4G/5G LEDs flashing in sequence (all LEDs turning on and off one after the other) means the device is attempting to connect to a mobile network operator. This suggests the modem is still registering or negotiating with the network at the operator level, even though data is already flowing through - this is a known nuance in Passthrough mode.
Since you’ve confirmed the connection is working via failover testing, the LEDs are not a reliable visual indicator of data connectivity in this mode - they reflect the router’s own WAN state, not the passthrough data flow.
If you’d like to verify what the modem is actually seeing, when you do get a chance to access the WebUI, you can check the mobile connection details under Status → Network → Mobile, which will show you the actual registration state, operator, and signal strength independently of the LED behaviour.
Hi Vilius thank you so much for taking the time to reply! I’m glad to hear that’s expected behaviour, although it would be more useful (IMO) to have the signal strength displayed when in passthrough mode, especially as the GUI is less easy to access in that mode. When you say the ongoing carrier negotiation is a “known nuance” does that mean it might get addressed in imminent f/w updates Many thanks, C.
Our RnD team has informed us that they were unable to replicate the issue in either Passthrough or Bridge mode.
Could you please provide the exact steps required to reproduce the issue?
Additionally, when the problem occurs, please share the output of the following command:
ubus call network.interface dump
This information will help us investigate the issue further.