Understanding the connection

Murmeli sends audio and video as directly as possible from one phone to the other. The app works out which route is available on its own. You do not have to configure anything. The badge at the top of the screen shows which one is in use right now.

The three routes

Live · Wi-Fi

Both phones on the same router. The data travels straight from device to device and never leaves your home. The fastest route. It even works when your internet line is down, because the router alone is enough.

Live · Directi

Different networks, still direct. You are out with mobile data and the two phones have found a route to each other. Here too, no server sits in between.

Live · Via serveri

Through Zurich. The network does not allow a direct connection, so our Swiss server passes the data on. It cannot read anything; everything stays encrypted and is never stored.

Tapping the info symbol explains what applies at any moment.

When the stream goes through the server

It works perfectly well, including when you are out. Audio and video arrive, alerts arrive, and it costs you no extra data: it is the same amount as on a direct connection, it simply takes a detour. The extra work is carried by the server, not by your phone.

What you may notice is a small delay. Our server is in Zurich, and that is deliberate: your data should not leave Switzerland. Within Europe the detour adds a few milliseconds that nobody notices.

Further away it becomes noticeable. If both phones are in Australia, for example, the data travels from Sydney to Zurich and back. The sound then arrives distinctly later.

Give the connection half a minute. After the initial setup Murmeli keeps checking whether a direct route is possible and switches over as soon as one appears. That can take up to thirty seconds. So if the badge first says “Via server”, it is worth waiting before you change anything.

What you can do yourself if you are far from Switzerland: bring both phones onto the same Wi-Fi. Then everything runs inside the house and the server is not involved at all. If that is not possible because you are out, turn the video off. Audio alone needs a fraction of the data and is far less sensitive to delay.

Opening the diagnostics

If you want to know exactly what is happening, Murmeli has a built-in readout. It is hidden on purpose so that it does not worry anyone in everyday use.

How to get there: on the parent device, while the connection is running, hold your finger on the word Murmeli in the header for about two seconds. Do not tap, hold.

The readout refreshes every second. None of it leaves your device, nothing is sent and nothing is stored.

Zustand: live
Verbindung: steht (Weg gefunden, verschluesselt)
Datenkanal: open
Audio empfangen: 7503 Pakete, 398 kB
Audio verloren: 40  Jitter: 0 ms
Weg: relay / relay  (ueber Relay, UDP)
Laufzeit: 26 ms
Wege geprueft: 15 gesamt, 3 erfolgreich
Eigene Wege:  host 6, srflx 2, relay 4
Gegenseite:   host 3, srflx 1, relay 1
  -> beide kennen sich, Firewall laesst nur den Relay durch
Neu ausgehandelt: 1x von 3, zuletzt vor 159 s
Vordergrunddienst: laeuft
TURN-Zugangsdaten: ok, 4 Adressen, vor 507 s

The readout is in German on every device, so that a screenshot sent to support always looks the same. Line by line:

`Zustand`	Whether monitoring is running. `live` is good.
`Verbindung`	Whether a route was found and the link is encrypted.
`Datenkanal`	The side channel for buttons and messages, such as the baby device’s battery level. `open` is good.
`Audio empfangen`	The key line for “I cannot hear anything”. If the packet count rises, audio is arriving and the problem is playback. If it stands still, nothing is arriving.
`Audio verloren`	Quality of the link. A few lost packets are normal, jitter below 30 ms goes unnoticed.
`Weg`	The core line, see below.
`Laufzeit`	Round trip time. Below 50 ms you notice nothing, above 200 ms it becomes audible.
`Wege geprueft`	How many options there were and how many worked. If it says `1 erfolgreich`, the route in use was the only one the network let through.
`Eigene Wege`	What each side offered. If `srflx` is missing on one side, that device does not know its public address.
`Neu ausgehandelt`	How often Murmeli has already tried to get off the server.
`Vordergrunddienst`	Whether the app stays awake when the screen is locked. On iPhone the line is called `Stille-Anker`. `STEHT` explains night-time drop-outs.
`TURN-Zugangsdaten`	Whether the app could reach the server.

The route line

Your device is on the left, the other one on the right:

`host`	reachable on the same network
`srflx` / `prflx`	reachable directly over the internet. Two spellings for the same result; they differ only in how the address was discovered.
`relay`	through our server

If either side says relay, the whole stream goes through the server. There is no such thing as half a direct connection.

In brackets after it stands the transport, UDP or TLS. UDP is better for audio. TCP and TLS resend every lost packet and hold up all the following ones while doing so, which you hear as stuttering.

The button at the bottom

Verbindung neu aushandeln searches for routes again from scratch. It tears nothing down; the current route carries on until a better one is ready. If the readout says relay and you are on a network where more should be possible, the button is worth a try. There are a few seconds of pause between two attempts during which the button does nothing. That is deliberate: a restart that cuts off the previous one makes things worse, not better.

Networks that close up

The most common reason for “it always goes through the server” is a walled-off network. Depending on the device and provider these are called guest access, guest Wi-Fi, guest network or simply public Wi-Fi. The technical setting behind it is usually client isolation or AP isolation.

You will run into them:

on your own router, when guest access is switched on. On many models the network is named almost like the main one, often with a “…-Guest” suffix, and it is easy to end up on it by accident
in hotels and holiday flats, almost always
at campsites and holiday parks
in cafés, restaurants and shopping centres
on company networks and in coworking spaces
in hospitals, railway stations, airports and on trains
in student halls and large housing complexes with a shared line

These networks separate the devices on purpose, so that a stranger’s laptop cannot reach your printer. That same separation is what stops the two Murmeli devices from finding each other.

The combination of normal Wi-Fi and guest access on the same router is particularly awkward. Both phones are a few metres apart, but the router will not let them talk to each other, and for the route around the outside it would have to accept a packet addressed to itself and bounce it back. Very few home routers can do that.

What helps: put both devices on the same network. If you have the choice, use the normal Wi-Fi for both.

Port 443, or why some networks work anyway

A phone has to know its public address, otherwise the other side cannot find it. To learn it, the phone briefly asks our server. That question normally travels over a port of its own, which many guest, hotel and company networks block: they only let through what websites use.

Since September 2026 Murmeli additionally offers the route over port 443, the same port as every encrypted website. As a result the app connects even on networks where it previously managed nothing at all. And because the phone can now ask for its address there too, a direct connection becomes possible again on some of those networks.

You do not have to set anything. The app chooses by itself.

What Murmeli does on its own

You do not have to intervene for the app to find the best route. It tries direct first and only takes the server when nothing else works. If the stream is going through the server, it then looks for a direct route three more times, and switches over if one appears. All you notice is the badge at the top changing.

If a device changes network, say from mobile data to the home Wi-Fi, Murmeli searches for routes again as well. And if the connection drops, the app rebuilds it on its own and keeps alerting you while it is missing. A silent failure is the one thing a baby monitor must never do.

Common cases

Why does Murmeli not connect at all?

First check whether both devices are on the same network. If one is on guest access and the other is not, pairing via the QR code often fails. Use the remote code instead, which works across different networks. In holiday flats and hotels it pays to pair once while the child is still awake.

Why does the audio stutter?

Look at jitter and lost packets in the diagnostics. If both rise, the link is poor, and turning video off gives noticeable relief. If the route line says TLS instead of UDP, the stream is running over a transport that is unfavourable for audio. You cannot change that yourself, but it explains the stuttering.

Why does it go through the server when both phones are at home?

Usually one device is on guest access. Check the Wi-Fi settings on both phones, the network names are often nearly identical. Second possibility: a device is on mobile data although Wi-Fi is available. That happens when the Wi-Fi is weak and the phone switches over by itself.

I cannot hear anything although it says “Live”. Why?

Look at the received audio packets in the diagnostics. If the number rises, data is arriving and the problem is with the sound itself: check the volume on the parent device, check the slider in the app, check whether mute is on.

Why does the connection drop at night?

On iPhone check the Stille-Anker line in the diagnostics; if it says STEHT, nothing is keeping the app awake. On Android the Vordergrunddienst has to be running, and battery optimisation for Murmeli should be switched off in the system settings. On both: the baby device belongs on the charger, and with flight mode on and Wi-Fi switched back on, no incoming call can interrupt the connection.

Where can I turn if nothing helps?

Open the diagnostics, take a screenshot and send it to support@murmeli-babyphone.ch. The readout contains no personal data, no addresses and no names, only counters and states. That is enough to place almost any connection problem without further questions.