Universal Control mouse and keyboard lag and disconnect

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Universal Control mouse and keyboard lag and disconnect

I'm having an issue using the shared mouse and keyboard feature as the mouse moves between my two machines (described here Universal Control: Use a single keyboard and mouse between Mac and iPad - Apple Support). It seems to trigger this issue that is described here (Sidebar scroll bar flashing intermittently - Apple Community) where the reason is that the mouse itself is reconnecting intermittently, triggering the display to show the scrollbar locations and states. This causes the mouse location itself to glitch and jump across the screen and causes the keyboard to randomly lag. It also will resize the content within windows quickly and suddenly responsively to the scroll bar appearing and disappearing. Occasionally, the machine will lose the mouse and keyboard completely requiring me to cycle the connection from the mouse to regain control.

Is there a way to at least disable the display trigger or a way to prevent the lag-jump and disconnects?

Mac Studio, macOS 15.7

Posted on Sep 1, 2026 1:28 PM

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Answer 1

Top-ranking reply

Owl-53

Level 10

114,911 points

Sep 5, 2026 4:57 AM in response to Rachel Mc

macOS does not provide a documented setting specifically for disabling the display response to a Universal Control or pointing-device connection change.

However, one setting is directly relevant to the scroll-bar resizing behaviour you described.

In System Settings >> Appearance, set Show scroll bars to Always.

Apple's AppKit documentation states that, when scroll bars are set to change automatically based on the input device, a change in the preferred scroller style can cause scroll views to update their layout.

Keeping scroll bars permanently visible may therefore prevent layout changes associated with automatic scroller-style changes. (Apple Developer)

For Universal Control, open System Settings >> Displays >> Advanced and temporarily turn off Automatically reconnect to any nearby Mac or iPad and Push through the edge of a display to connect a nearby Mac or iPad.

Apple states that, with either option disabled, you can still connect manually through Control Center >> Display or the Add Display (+) menu in Displays settings. (Apple Support)

If the lag, cursor jumping, or loss of shared input continues, Apple's documented troubleshooting includes turning Universal Control off on each device, restarting the devices, and then turning Universal Control back on.

Apple also recommends checking for VPN or third-party security software and ensuring that the Mac firewall is not configured to block all incoming connections. (Apple Support)

The more relevant Apple reference is:

Universal Control: Use a single keyboard and mouse between Mac and iPad — Apple Support

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Answer 2

WheelieNick

Level 9

59,443 points

Sep 4, 2026 12:34 AM in response to Rachel Mc

You can stop the content resizing and visual flashing by changing your Mac's scroll bar settings to stay permanently visible, while resolving the underlying disconnect requires addressing hardware interference or connection stability.

When macOS dynamically hides and shows scroll bars based on pointer state or connection events, intermittent drops cause the sudden visual resizing you described.

Open System Settings (or System Preferences) on your Mac.
Go to Appearance.
Locate Show scroll bars and change the setting from Automatically based on mouse or trackpad to Always.

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