TRB500 RTMP issue with Blackmagic encoder

Networking Solutions Issue
1

Hello,

I am experiencing a live streaming issue using a TRB500.

Setup:

  • TRB500 with mobile network sim cards (tested with multiple operators)

  • Blackmagic Streaming Encoder and Web Presenter

  • RTMP streaming to YouTube / other platforms

Problem:

  • Streaming RTMP works perfectly with OBS with the 5G network from the TRB

  • Streaming works with Blackmagic Encoder on fiber or other networks

  • But fails with Blackmagic when using the TRB500 with the 5G network (cache fills up, stream does not start)

This suggests a network-related issue affecting Blackmagic devices only.

A network engineer suggested capturing traffic using TCP dump (.pcap) to compare OBS vs Blackmagic behavior.

Before doing this, I would like to confirm:
Is TCP dump on TRB500 (WAN or Any interface, ports 1935/443, short capture) the correct method?

Has anyone experienced similar issues with RTMP and Blackmagic devices over mobile networks?

Thanks for your help.

Maxence

3

Greetings,

Apologies for the delayed response.

Yes, that is correct. First, you will need to install TCPdump by navigating to System → Package Manager .

Once installed, you can start a packet capture by going to System → Maintenance → Troubleshoot → TCP Dump .

I recommend selecting all Interfaces, as this will allow you to trace packets as they enter the TRB500 through the LAN interface (from the Blackmagic device) and exit through the WAN/Mobile interface. This should help determine whether the TRB500 is dropping or fragmenting any packets.

You can also try reducing the MTU on the mobile interface. To do this, navigate to Network → WAN , edit the active interface and under Advanced Settings, adjust the Override MTU value. I suggest testing values such as 1420, 1400 and 1360 .

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Best Regards,
Justinas