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How to make video calls work on a bad network

Quick fixes first, then a plain-English explanation of what's going wrong, including NAT, STUN and TURN, and a troubleshooting table for the most common problems.

By the Asyncbit teamReviewed 7 min read

To make video calls work on a bad network, reduce what the call has to send and give it the most stable path you can: turn your camera off or ask others to, stop background uploads, move closer to the Wi-Fi router or to a window for mobile signal, and try switching between Wi-Fi and mobile data. If a call rings but never connects, the network is usually blocking a direct connection, and switching networks is the quickest test.

Those fixes work in any calling app. The rest of this guide explains why they work: what actually breaks calls, how your device finds a path to the other person through routers and firewalls, and what a relay server is for. Understanding that makes the troubleshooting table at the end much easier to use.

Quick fixes to try first

  1. Turn off your camera. Video needs far more data than audio. Audio-only often stays clear on a connection where video falls apart.
  2. Pause uploads. Cloud photo backup, file sync and big downloads compete with the call, and uploads hurt most.
  3. Get closer to the router, or away from walls. Wi-Fi weakens quickly through walls and floors. On mobile data, a window or a higher floor can make a real difference.
  4. Switch networks. Try mobile data if Wi-Fi is bad, or Wi-Fi if data is bad. Some networks block the kind of traffic calls prefer.
  5. Turn off your VPN for the call, unless you need it. VPNs add distance and sometimes block the ports calls use.
  6. Use headphones. They stop echo, which apps otherwise try to cancel by cutting audio.
  7. Close and reopen the app, or refresh the browser tab, and check that it still has camera and microphone permission.

What actually breaks a call

A speed test measures how much data you can download in a burst. Calls care about something different: a steady, two-way stream of small packets arriving on time. Four things decide whether that works.

Network problems that affect calls
Low bandwidth
What it means:Not enough capacity for the data the call is sending
What you notice:Blurry or frozen video; the app lowers quality or turns video off
High latency
What it means:Each packet takes a long time to arrive
What you notice:Delay; people talk over each other
Jitter
What it means:Packets arrive at uneven intervals
What you notice:Choppy or robotic audio even when speed seems fine
Packet loss
What it means:Some packets never arrive
What you notice:Words cut out, video smears or freezes, calls drop

Upload matters as much as download. Everything you say and show has to go out through your upload, and many home and mobile connections upload much more slowly than they download. If other people see you freezing but you see them fine, your upload is the likely bottleneck.

How a call finds its way: NAT, STUN and TURN

Most browser and app calls today use WebRTC, a standard that tries to send audio and video directly between the people on the call. A direct, peer-to-peer path is usually the fastest. The problem is that most devices can't be reached directly from the internet.

NAT (network address translation) is the reason. Your router shares one public internet address among every device in your home, and your mobile carrier often does the same for many customers at once. That's fine for browsing, because your device starts the conversation. A call is different: two devices, each hidden behind its own router, have to find each other.

  1. 1

    STUN: find out how you look from outside

    Your device asks a STUN server, “What address do my packets appear to come from?” Both sides exchange these addresses and try to connect directly. On many home networks this works.

  2. 2

    When direct fails

    Strict firewalls on office, hotel and some public networks block the traffic calls use, and some carrier NATs change your outside address in ways that make a direct path impossible. The call then rings but never connects, or connects with no audio.

  3. 3

    TURN: relay the call

    A TURN server sits on the public internet and both devices connect out to it. It passes the audio and video between them. Because each device only makes an outgoing connection, this gets through networks where a direct path can't.

Relaying adds a little delay, since traffic goes via the relay, and it costs the provider bandwidth. That's why apps try direct first. But an app with a TURN relay is often the difference between a call that connects on office Wi-Fi and one that doesn't. If a call connects fine at home and never at work, the missing piece is usually a relay path the network allows.

Troubleshooting common call problems

Call symptoms, likely causes and what to try
Rings but never connects, or stuck on “connecting”
Likely cause:Network blocking a direct path; no relay available
What to try:Switch to mobile data; turn off VPN; try a different app to confirm it's the network
Works on mobile data, fails on Wi-Fi
Likely cause:Firewall on that Wi-Fi network
What to try:Use data for calls on that network, or ask the network admin whether calling apps are blocked
Connects but nobody can hear anyone
Likely cause:Media can't flow even though signalling worked; or mic permission missing
What to try:Check microphone permission; switch networks; rejoin the call
Your video freezes for others, theirs is fine
Likely cause:Your upload is too slow or busy
What to try:Pause uploads and syncing; turn your camera off; move closer to the router
Robotic or choppy audio
Likely cause:Jitter or packet loss
What to try:Move away from crowded Wi-Fi; use a wired connection on a laptop if you can; turn video off
Long delay, people talk over each other
Likely cause:High latency; distant VPN or relay
What to try:Turn off VPN; switch networks; agree to pause briefly before replying
Echo
Likely cause:Someone's speaker feeding back into their mic
What to try:That person uses headphones or turns their volume down
Call drops when the phone screen locks
Likely cause:Battery saver or background limits closing the app
What to try:Exempt the app from battery optimization; use picture-in-picture if your app offers it

Why group video calls struggle first

Every extra camera is another video stream your device has to receive and decode, and in some call designs each person also sends a separate stream to every other participant. On a weak connection, a two-person call can be fine while a six-person video call falls apart. That's why many apps cap how many people can be on video at once.

  • Ask people who aren't speaking to turn their cameras off.
  • Keep a group call audio-only when several people are on mobile data.
  • Have the person with the weakest connection join by audio only.
  • Close other tabs and apps on older phones and laptops; decoding video is hard work for them.

How calls work on Asyncbit

Voice and video calls on Asyncbit start from a chat, one-to-one or in a group. They use WebRTC with a TURN relay, so calls can connect on mobile data and restrictive networks. Group calls take up to 8 people, with video for up to 4; larger calls continue as audio. Calls work in the browser and in the Android app, which has picture-in-picture, and each call leaves a short summary line in the chat. There is no iOS app. For how calls fit alongside group chats, see the group chat and calls use case, and if a call still won't connect, contact support.

The short version

  • Turning video off and pausing uploads fixes most calls on a weak connection.
  • Calls need a steady two-way stream, so upload speed, jitter and packet loss matter more than download speed.
  • NAT hides devices from each other; STUN helps them connect directly, and a TURN relay carries the call when they can't.
  • If a call works on one network and never on another, the network is blocking it; switch networks to confirm.

Frequently asked questions

Why does my video call freeze when my internet speed test is fine?
Speed tests mostly measure download bursts. Calls need steady upload and low jitter and packet loss, which a speed test doesn't show. Background uploads and crowded Wi-Fi are common culprits.
Is a relayed call less private than a direct one?
Not inherently. WebRTC encrypts call media in transit whether it goes direct or through a relay; the relay passes the encrypted packets along.
Why do calls work at home but not on office or hotel Wi-Fi?
Those networks often have firewalls that block the traffic calling apps prefer. Apps with a TURN relay can usually still connect; otherwise, mobile data is the workaround.
Does audio-only really use less data?
Yes, by a large margin. Voice needs only a small fraction of the data video does, which is why audio often stays clear when video fails.

Call from the conversation

Voice and video calls on Asyncbit start from inside a chat, one-to-one or in a group, in the browser or on Android.

Join and make your first call

Asyncbit features in this guide

Terms explained in the glossary

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