Why video calls lag when someone uploads photos

Your video call freezes or the audio breaks up whenever someone starts uploading photos. The internet may still look fast, but a full upload can make the connection slow to respond.

The Bufferbloat Test checks how much connection delay increases while data is being uploaded or downloaded. It can show whether your connection struggles under load, then you can narrow down whether photo backup is the trigger.

Test delay while the connection is busy

1. Open the Bufferbloat Test on a computer connected to the same network as the video call. If possible, use the same Wi-Fi network or wired connection that has the problem.
2. Run the test when nobody is making a call or moving large files. Let it finish and note the grade, from A+ to F, and the change in delay during the upload portion.
3. Repeat the test later while photo backup or another large upload is active, but not during an important call. Keep other network activity as similar as possible between runs.
4. Compare the two results. A much worse grade or a larger delay during the busy period suggests that upload traffic is affecting how quickly other data gets through.
5. For a direct check, make two short calls under similar conditions, one with photo backup paused and one with it running. Note whether the video or audio becomes worse only during the upload.

The test exchanges test data with our server to measure delay under load. It does not inspect the photos or identify which app is sending them.

What the result means

The grade gets worse when the connection is busy

Your router or internet connection may be holding data in a queue while the upload is full. Video calls need small packets to travel back and forth promptly. If those packets wait behind a long queue of photo data, the call can freeze or sound choppy even though the upload eventually completes. This is commonly called bufferbloat. The article Why bufferbloat gets worse during uploads explains why upload traffic can cause this delay.

The grade is poor even when nobody is uploading

The connection may have high delay under load even without photo backup. A different device, cloud sync, a game download, or a router setting could be filling the upload. Repeat the test when the network is quiet, and check whether any device is sending large files.

The grade stays good, but the call still lags

The problem may be Wi-Fi interference, a weak connection between the calling device and router, or the call app itself. A browser test cannot see which app is uploading or diagnose the video-call service. Check whether the call improves near the router or over a wired connection, and test the call with photo backup paused.

The call improves when photo backup is paused

That is strong evidence that the upload is contributing to the problem. It does not necessarily mean the internet plan is faulty. One device can use most of the available upload capacity, especially when it sends a batch of full-resolution photos. See Why one device can use all your upload bandwidth for more about that situation.

How to reduce the lag

1. Pause photo backup during calls. Use the photo or cloud storage app's pause or backup controls, then resume the upload afterward. On an iPhone, check Settings › Apps › Photos and the backup controls in the relevant photo service. On Android, open the photo app's profile menu, then Photos settings › Backup; wording differs between apps. Pausing inside the app is more dependable than assuming the phone will delay the upload on its own.
2. Limit the upload rate. Check whether the photo backup app, cloud sync app, or router lets you set a bandwidth limit or schedule uploads. Leave enough capacity for the call, and change one setting at a time so you can tell whether it helped. If the upload limit is in the router, the exact menu depends on its model.
3. Use router traffic management if available. Look for Smart Queue Management, SQM, or a setting that prioritizes calls. These features manage the queue so one large upload is less likely to hold up everything else. If you can set a maximum upload rate, use a starting point below the sustained upload speed you measure, then retest and adjust. Not every router has effective queue management.
4. Keep large uploads from starting automatically before calls. If a sync app launches with your computer, Windows 11 has Settings › Apps › Startup. macOS has System Settings › General › Login Items & Extensions. Turning off automatic launch can prevent a new upload from starting after sign-in, but it does not stop one already in progress. Pause the upload in the app itself.
5. Improve the calling device's connection. If possible, connect the computer to the router with Ethernet. On Wi-Fi, move closer to the router and avoid testing from behind several walls. This can fix a weak local link, though it will not create more internet upload capacity if the connection to your provider is already full.
6. Check the router and internet plan. Install a router update if one is available, then repeat the test. If the upload is consistently slow or delay remains high with no other traffic, contact your internet provider and share the results. Ask whether your plan has a low upload rate or whether the line has a fault.

Why upload speed alone does not explain the call

Upload speed measures how much data can be sent in a given time. Delay measures how long a packet waits to reach its destination and return. A connection can have a reasonable upload speed but still feel unresponsive when a large transfer fills the router's queue. That is why a speed result alone may not explain a call that breaks up only during photo backup.

Use the Bufferbloat Test to check how delay changes under load, then pause or limit the photo upload and see whether the call becomes stable.