SRTLA bonding for stable IRL streams
Bond multiple networks (LTE + Wi‑Fi), when bonding helps, and how to tune buffer and packet loss.
Build a bonding router kit for IRL streams
Short answer: A “bonding router” combines several uplinks – such as LTE modems, Wi-Fi and Ethernet – at the network layer. For a single SRT/SRTLA stream to IRL.com.de, the real bonding happens in the app instead: Moblin and IRL Pro spread packets across multiple interfaces using SRTLA. A multi-WAN router mainly gives you failover and load balancing between connections; a single SRT connection usually stays on one uplink. A router kit therefore makes sense mainly for encoders without their own mobile data or Wi-Fi, or as an extra safety net.
Router bonding and SRTLA are not the same
| Property | Multi-WAN router | SRTLA (app) |
|---|---|---|
| Layer | Network layer: uplinks on the router | Application layer: between app and relay |
| Bonding one connection | Typically no (flow hashing) | Yes, packet aggregation |
| One uplink fails | Failover and redistribution | Other paths keep carrying traffic |
| Link to the encoder | A single line (Ethernet or Wi-Fi) | The app uses multiple interfaces itself |
| Typical use | Ethernet encoder, backup uplink | Mobile IRL with several networks |
Flow hashing: multi-WAN routers usually balance per connection, not per packet. A single SRT stream therefore generally stays on one uplink until that uplink fails. True packet bonding for one stream is done by SRTLA in the app – see SRTLA bonding.
When a router kit is worth it
- Your encoder only has Ethernet (camera, laptop, hardware encoder) and needs a mobile internet uplink.
- You want a second uplink as backup while the app keeps sending over the phone.
- You prefer to manage several SIMs centrally on the router instead of on the phone.
- Not needed: if your phone plus app already bonds SRTLA over mobile data and Wi-Fi, an extra router is usually unnecessary.
Parts list for the kit
- A router with multi-WAN support (for example OpenWrt with mwan3) and USB ports for LTE/5G sticks.
- Two or more LTE/5G modems with SIMs – ideally from different carriers so one provider outage does not take down both uplinks.
- External antennas or at least good placement: metal and vehicle bodies weaken mobile reception.
- A short Ethernet cable to the encoder.
- A sufficiently sized USB-C PD power bank – router and modems draw power continuously.
- Active cooling or a shaded spot, because router and modems run hot on the move.
- Hook-and-loop tape, cable ties and a weatherproof bag for the backpack.
Setup in short
- Insert the SIMs and confirm in the router UI that each uplink is online on its own.
- Configure the multi-WAN policy: prioritise one strong uplink and keep the others as failover.
- Connect the encoder to the router via Ethernet and test internet access.
- Create a stream in the panel with SRT / SRTLA ingest and copy the URL and stream key.
- If your encoder supports SRTLA, configure bonding in the app – the router then only supplies one stable path.
- Start streaming and watch packet loss, bitrate and RTT in the panel.
Buffer, bitrate and expectations
- Router bonding does not create bandwidth: usable bitrate stays limited by the sum of the active uplinks.
- Buffer as with any bonded setup: 1,000–2,000 ms as a conservative mobile start, with a practical ceiling around 2,500 ms (roughly 4× RTT).
- Overly aggressive failover thresholds switch between networks needlessly – prefer slightly slower settings.
- A weak uplink in the bundle can raise overall latency. Check which connection is actually being used.
Watch the numbers: read bitrate, latency and packet loss on the dashboard – see the statistics guide and SRT latency and buffer for details.
What router bonding does not fix
- It does not replace app-level SRTLA: for a single stream there is usually no packet aggregation across uplinks.
- Flow hashing can pin an SRT stream to one uplink even when another one is free.
- A wrong stream key or wrong protocol in the panel remains a panel-side mistake – the router cannot change that.
- If every uplink is saturated at the same time, bundling does not help either.