Bonding: Wi-Fi and cellular in one stream in five minutes

Set up srtla bonding in LOLS IRL, read the per link indicators while you stream, and know what to expect the first time a network dies on you.

Bonding sends your stream over every network your phone has at once. It is the difference between a stream that ends when Wi-Fi drops and one that carries on over cellular without you touching anything. Set it up once and it is just how you go live.

What you need first

Setting it up

  1. Get your receiver details. For a free relay that is a key from relay-auth.lols.gg, which arrives already shaped as a stream id. For your own box it is the hostname, the UDP port and whatever stream id your server expects.
  2. Open Streams and add a destination. In the app, go to Streams, tap +, and choose SRTLA from the three protocol chips. SRT is one connection to your own receiver, RTMP goes straight to a platform, SRTLA is the bonded one.
  3. Fill in the host and port. With a relay, tap your region chip and the host, port and name fill themselves in. The nearest region for your SIM's country carries a star. With your own receiver, type the public hostname and the UDP port it listens on.
  4. Paste your key into Stream id. This is the field people get wrong. A relay key already contains its publish: prefix, so paste it whole into Stream id, not into the name and not onto the end of the host.
  5. Leave latency at 2000 ms to start. That is the default and it is a sensible one. Higher rides out a rougher signal, lower cuts delay but leaves less room to resend a lost packet. Once you are live the app shows the round trip it is actually measuring and suggests a figure to match, so tune it later with real numbers rather than guessing now.
  6. Save, and make sure the destination is switched on. A destination that is saved but not enabled is the quietest way to not be streaming.
  7. Go live, then expand the stats. Tap the stats overlay on the live screen to expand it. You want to see one row per link: wifi and cell, each with its own bitrate and round trip. Two rows means you are bonded. One row means you are not, and the mistakes below will say why.

Reading the indicators

Collapsed, the overlay is a health dot, your bitrate, encoder frame rate, round trip and how long you have been live. Tapping it opens the detail:

ReadingWhat it tells you
send bufferThe leading indicator, and the one to watch. The buffer fills before the picture stutters, so a rising figure is your warning that a link is struggling, not a report that it already failed.
targetThe bitrate adaptive bitrate is currently aiming at, which drops and climbs back on its own as conditions change.
dropped and retransmitPackets lost and packets resent. A few retransmits on cellular are normal, a climbing drop count is not.
One row per linkLabelled wifi, cell or eth, each with its own bitrate and round trip, so you can see which network is carrying what.
The dot on each link rowGreen is active and carrying traffic, amber is connecting or stalled, red is dead. A red row while the stream stays up is bonding doing its job.
One row per destinationNamed, so if you are sending to several places you can see which one is down while the others are fine.

What happens when a link drops

Nothing dramatic, which is the point. The failed link's row turns red, the remaining links pick up the traffic and the stream stays connected. When the network comes back, that link re-registers with the receiver and rejoins the group on its own. You do not stop, restart, or touch anything.

Two things worth setting expectations on. First, the surviving link has to carry the whole stream, so if your bitrate was only ever going to fit across a good Wi-Fi, adaptive bitrate will step down while cellular is doing the work and climb back afterwards. Second, bonding is resilience and not extra speed: your links are never added together into a bigger pipe. Set your bitrate to what one good link can carry and you will barely notice the handover.

Test it on purpose, before you need it. Go live on bonding from home, wait until the stats look steady, then turn Wi-Fi off for a minute and watch. You will see the wifi row go red, the cell row take over, and the whole thing come back when you switch Wi-Fi on. Ten minutes of this is worth more than any amount of reading, and it is far better to learn it in your kitchen than halfway through a stream.

The mistakes that cost people their first attempt

Pointing at an address on your own network

This is the big one. A receiver at 192.168.1.50 is reachable over your Wi-Fi and from nowhere else, so your cellular link cannot register and you are not bonded, you are on Wi-Fi with extra steps. The destination has to be a public hostname or address, which means a relay, a hosted box, or a UDP port forward on your router pointed at your machine and addressed by your router's public address. Same rule for a laptop on your desk.

Leaving the stream id blank or half pasted

Receivers authenticate publishers, so an empty or truncated stream id gets you a connection that goes nowhere. Paste the key whole, including its publish: prefix, into the Stream id field.

Expecting more bitrate

Two links do not add up. If you set a bitrate that only your Wi-Fi could ever carry, the stream will look worse the moment cellular is doing the work, and you will blame bonding for the opposite of what it did. Bonding keeps you live. Bitrate is a separate decision.

A VPN running on the phone

A VPN captures every socket on the device, so the app cannot open one per network and there is nothing left to bond. The stats say so directly when it happens. Turn the VPN off, or exclude LOLS IRL from it in the VPN app's own settings.

Sending srtla at a plain SRT server

SRTLA needs a receiver running srtla_rec, which is what puts the links back together. A plain SRT listener does not understand the group registration. Use a relay, or run srtla_rec in front of your SRT server as the self-hosting guide describes.

Picking a relay on the far side of the world

Distance costs you delay you can never get back, and a long enough round trip can stop the connection establishing at all. Pick the nearest region: the app stars the one that matches your SIM's country.

Once it is working

Next: using the free relays