Upload is slow on a Mac but download is fine

Upload and download use different limits. A plan can give much less upload than download, and one busy app can fill the upload alone. This guide measures each direction and compares the Mac with other paths.

Fix this with your agentCopies a prompt for Claude Code, Codex or any agent that can use Terminal.

My Mac has this problem: Upload is slow on a Mac but download is fine. Read https://kilobat.app/guides/slow-upload-mac.md and work through it with me. Install the Kilobat CLI if it’s missing: brew install seifip/kilobat/kilobat. Run the guide’s Terminal and kilobat checks yourself and tell me what you find. List the steps only I can do. Ask before you change any setting.

Applies to: macOS 12 Monterey and later for networkQuality. The System Settings steps are for macOS 14 Sonoma and later.Checked: 7 November 2026

Symptoms

Speed tests show normal download speed but very low upload speed.
Other devices on the same network upload faster than the Mac.
Video calls freeze when you share your screen or camera, but downloads work.
File uploads, iCloud sync or backups take much longer than before.

Likely causes

The plan has a low upload speed. Many broadband plans give much less upload than download. Compare your result with the upload speed in your contract.
Another app already uploads. Photo sync, backups and cloud drives can fill the upload. Then other uploads and calls slow down.
Latency rises under upload load. Large buffers in the router or modem add delay when the upload is full. See Bufferbloat: calls lag when the network is busy.
The Wi-Fi link is weak for sending. A weak signal or a crowded 2.4 GHz channel can slow uploads from the Mac more than downloads.
A VPN or network extension. A VPN, proxy or filter app handles each packet. A slow tunnel or server limits the upload.
Router quality of service settings. A router rule can limit upload for one device or for the whole network.

How to check

Measure upload and download one after the other. Look at each direction’s capacity and responsiveness.
```
networkQuality -s -v
```
Measure the upload only.
```
networkQuality -d
```
Test over a specific interface, such as Wi-Fi or Ethernet. Use the name from networksetup -listallhardwareports.
```
networkQuality -s -I en0
```
Run the same test on another device on the same network. If it is also slow, the Mac is not the cause.
Disconnect any VPN, then test again.
Hold the Option key and click the Wi-Fi icon. Note the band, the signal (RSSI) and the transmit rate.

How to fix it

Pause the app that uploads, or let it finish. Photos, iCloud Drive and Time Machine are common.
Move closer to the router, or use a 5 GHz or 6 GHz network. See 2.4 GHz, 5 GHz and 6 GHz Wi-Fi on a Mac.
Connect an Ethernet cable for a test. If upload is then fast, the Wi-Fi link is the cause.
Update the VPN app, or try a different VPN server or protocol.
Remove network extensions that you no longer use. See Little Snitch, LuLu and other network extensions conflict on a Mac.
In the router, look for quality of service or bandwidth limits. Remove limits on the Mac.
If the router has smart queue management, turn it on. See Bufferbloat: calls lag when the network is busy.
If every device is slow and the router is not the cause, contact your provider with your test results.

The exact menus for your router, from FRITZ!Box and Xfinity to eero and Livebox: router guides.

With Kilobat

Show apps that upload a lot now, with their rate and how much they sent.
```
kilobat uploads
```
Run a speed test with loaded latency. It gives upload speed and call verdicts.
```
kilobat speedtest
```
Compare two saved tests. The output lists differences in network, Wi-Fi band, signal, VPN and other traffic.
```
kilobat speed-compare
```
Show what one app sent and received this week.
```
kilobat bandwidth Photos week
```
With Kilobat Pro, hold a large upload until a faster network is available.
```
kilobat uploads hold Photos --until fast
```

Questions

Why does networkQuality show a different upload than a website test?

Each tool uses its own servers and number of connections. Compare results from the same tool over time.

Is it normal for upload to be lower than download?

On many cable, DSL and mobile plans, yes. Check the upload speed in your contract before you look for a fault.

Sources

networkQuality(8), man page installed with macOS 27.2
Apple Support: Test Wi-Fi networks with Apple Network Responsiveness
Apple Support: Recommended settings for Wi-Fi routers and access points
Bufferbloat.net: Introduction

Checked on 7 November 2026.