RUTX11 firmware update: Cannot read RTMP handshake

After switching my RUTX11 to firmware RUTX_R_00.07.04.4 (and internal modem to EG06ELAR04A20M4G) last week, I am having a problem with a linux bash script connecting from an external server via OpenVPN to my RUTX11 and streaming via RTMP.

Error message on the external server:
"Cannot read RTMP handshake response rtmp://IP-address:port/bcs/channel0_ext.bcs?channel=0&stream=2&user=XXX&password=YYY: End of file

The strange thing is I can ping this webcam within my RUTX11 network (connected via LAN RJ45) from the external server without a problem. On my notebook also connected via OpenVPN to my RUTX11 the stream is working fine in VLC player using the same aforementioned stream address.

Beside this all my (Wifi) IoT devices within my RUTX11 network suddenly stop connecting to the cloud appr. once a day without any reason. They devices do not come back in the cloud until a reboot of the RUTX11 from myside. After the reboot the devices are working fine reporting to the cloud for almost one day. Also these devices I can ping at any time from inside the RUTX11 network from the router and also from external. The ping is successful also during the time the devices do no more connect to the cloud. This problem was not existing before the firmware update.

As I am no tan expert: Can someone help me to identify and solve the problem? I can access my RUTX11 via Teltonika webUI and also command line via SSH. I am ready to start putting network commands etc. to identify the problem at any time.
But I am 1000km away from the router…

Thank you very much in advance! This is really annoying.

no-one an idea?

What are the outputs of:
ifconfig qmimux0 | grep MTU
gsmctl -A 'AT+QMTUINFO'


With a default MTU of 1500 bytes there is no need to override it.
Could you clear this field and retry ?

Thank you flebourse. I just deleted the MTU line in the GUI.

It is normal that the following commands do not give any output?

Hi, quick tip - try to use this command:
ifconfig -a | grep -i "mtu"
The -i flag tells grep to ignore case sensitivity.

Also, I think RUTX11 uses wwan0 as mobile interface name instead of qmimux0? Try to look for that.

This is a little strange indeed.
What is the output of ifconfig ? (hide public addresses if applicable).

The interface is wwan0 not qmimux0 on this model. Sorry for the noise.
I was thinking of a bad fragmentation / defragmentation issue but that doesn’t seem to be the case.
What is the output of:
tcpdump -i wwan0 -n -v 'port xxx'
xxx beeing the port number as reported in the error message in the initial post ?

1935, if you haven’t changed the defaults.

currently I am not able to connect to the router at all. The last few days I at least were able to connect via SSH.
I will need to wait until a scheduled reboot of the device during the night and will come back tomorrow morning. Thank you flebourse for your kind assistance so far. Would highly appreciate if you could try to support me further from then. Many Thanks!

Hello! Just a quick response:

Around 48h ago I updated my RUTX11 to the latest (beta) firmware version RUTX_R_00.07.04.5 via file (manually downloaded from Teltonika Website) and I set the MTU overwrite option in the WebUI to 1280 and then reboot.

Since this everything is running without problems so far. Also my IoT devices are working fine again.

If you do not hear from me again within this topic, the problem is solved.

Thanks for your support!

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