macOS Sequoia 15.6+ and Tahoe: Network Performance Degradation - Workarounds – Softron Support Desk

In macOS Sequoia 15.6 or later, as well as all versions of Tahoe (as of December 2025), a known operating system issue impacts network performance when using certain macOS libraries. This can affect all our applications when using remote control, and WebUI control.

The solution below disables TCP Segmentation Offload (TSO), which mitigates this performance issue at the OS level.

⚠️ WARNING: The following steps require using the Terminal application and the sudo command to make system-level changes. Only proceed if you are comfortable with command-line operations and have administrative privileges.

Background

TSO allows the network interface card (NIC) to handle packet segmentation—splitting data into Ethernet-sized packets. Disabling TSO forces this task to be handled by the CPU instead. Based on our findings, this hardware-based packet segmentation appears to be affected by a bug introduced in recent macOS versions.

Softron Launch Daemon (Recommended)

The easiest solution is to install a launch daemon we have created as a workaround. This launch daemon automatically disables TSO at startup.

Download link: https://softron-downloads.s3.amazonaws.com/apps/Softron_Disable_TSO.pkg

Manual fix

If you prefer to apply the workaround manually, the section below explains the required command-line steps and how the launch daemon above was implemented.

Temporary Fix

For a quick test, you can run this command in Terminal. Note that this change will be undone the next time the system restarts, so you would need to run it every time the Mac restarts.

sudo sysctl -w net.inet.tcp.tso=0

Permanent Solution: Create a Launch Daemon

To ensure the fix is applied automatically every time the system boots, you can create a system-level Launch Daemon, the same way we did ours above.

Using terminal, we need to make a .plist for the Launch Daemon

sudo nano /Library/LaunchDaemons/local.system.disable-tcp-tso.plist

This needs to be pasted and saved for the Launch Daemon:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN"
 "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>Label</key>
    <string>local.system.disable-tcp-tso</string>

    <key>ProgramArguments</key>
    <array>
        <string>/usr/sbin/sysctl</string>
        <string>-w</string>
        <string>net.inet.tcp.tso=0</string>
    </array>

    <key>RunAtLoad</key>
    <true/>

    <key>LaunchOnlyOnce</key>
    <true/>
</dict>
</plist>

Once pasted:
Press CTRL + O (to write/save the file). Press Enter to confirm the file name.
Press CTRL + X (to exit the nano editor).

Run these two commands to set the correct root ownership and permissions on the file:

sudo chown root:wheel /Library/LaunchDaemons/local.system.disable-tcp-tso.plist
sudo chmod 644 /Library/LaunchDaemons/local.system.disable-tcp-tso.plist

Run the following command to load the configuration immediately and ensure it runs on every future system boot:

sudo launchctl bootstrap system /Library/LaunchDaemons/local.system.disable-tcp-tso.plist

Verification

To confirm the network setting is active, run this command in Terminal:

sysctl net.inet.tcp.tso

The output should show a value of 0:

net.inet.tcp.tso: 0

This confirms the fix is in place and should mitigate the network performance issue.

Reverting the Fix (Removal)

If a future macOS update fixes the underlying issue, or if you need to remove this script for any reason, run the following commands in order:

sudo launchctl bootout system /Library/LaunchDaemons/local.system.disable-tcp-tso.plist
sudo rm /Library/LaunchDaemons/local.system.disable-tcp-tso.plist