Universal Control Lagging? One Mouse for Multiple Macs – Wi-Fi or Cable

With EdgeFlow you control several Macs with a single mouse and keyboard: push the pointer over the edge of the screen and it appears on the Mac next to it. By default this works wirelessly and directly between the computers – no shared Wi-Fi network and no shared Apple Account required. Most of the time it feels as if the mouse were plugged straight into each Mac. Now and then, though, the pointer stalls for a moment. This article explains where these stalls come from, what you can improve on your Wi-Fi, and why a network cable is the most reliable solution.

What about Apple's Universal Control?

macOS comes with its own solution, Universal Control: one Mac can control up to two other Macs or iPads nearby. For this, all devices must be signed in with the same Apple Account, be no more than about 10 metres (30 feet) apart, and have Bluetooth, Wi-Fi and Handoff turned on. Apple's instructions only list wireless connections for it.

If Universal Control works reliably for you and all your devices use the same Apple Account, you don't need anything else. EdgeFlow helps in two places where Universal Control doesn't: it needs no shared Apple Account – for example for a personal and a work Mac – and it can connect your Macs over a network cable.

How EdgeFlow connects your Macs wirelessly

For the direct wireless connection EdgeFlow uses AWDL (Apple Wireless Direct Link) – the same technology AirDrop uses to transfer files between Apple devices. The Macs need neither a router nor a shared network. The range is the same as AirDrop's: meant for the same desk or the same room.

The catch: AWDL has no antenna of its own. It shares the Mac's Wi-Fi radio with the normal Wi-Fi connection to your router. And that radio can only send and receive on one channel at a time.

Where the brief stalls come from

Because both connections share one radio, it switches back and forth at short, regular intervals between the router's channel and the channel of the direct connection. While it is "elsewhere", the mouse movements wait in the queue. When the radio comes back, they are delivered in one go.

What you see: the pointer stops for a fraction of a second – in our measurements typically around a quarter of a second – and then jumps to the right place. These stalls don't happen all the time but in short series: a few in a row, after which the connection runs cleanly again.

Worth knowing:

• It is not your Mac's processing power. The mouse movements are sent on time; they wait on the wireless link.
• The connection is not slow in general. Between the stalls, movements arrive within a few milliseconds.
• It affects the wireless link, not individual devices. We observed the stalls on different Macs, including on connections that weren't carrying any mouse movements at the time.

How to improve the Wi-Fi connection

Over the air, the stalls can't be avoided completely. These settings make them less frequent:

• Keep Wi-Fi turned on on all Macs. Without Wi-Fi there is no direct connection – not even when the Mac is connected to the network by cable. EdgeFlow then shows the Mac but can't connect to it.
• Set your router to a fixed 5 GHz channel, ideally 44 or 149. The direct connection between Apple devices prefers these channels. If your router is on the same channel, the radio has to switch less often. Turn off automatic channel selection in your router for this.
• Avoid DFS channels (5 GHz channels 52 to 144). The direct connection can't run on these channels, so the radio has to jump back and forth constantly. In our tests, moving from a DFS channel to channel 44 noticeably reduced the stalls.
• Keep the Macs close together. EdgeFlow is meant for computers at the same workplace, not in different rooms.
• Avoid large Wi-Fi transfers while you work. Big downloads, backups or video streams over the same Mac's Wi-Fi put extra load on the radio.

Even with the best settings it remains a wireless link: in our measurements the brief stalls still occurred when all Macs involved and the router were on the same channel – less often, but not never.

The reliable solution: a network cable

Over a network cable there is no shared radio, no channel switching and no wireless interference. In our comparison measurements – same Macs, same movement patterns – the stalls practically disappeared over cable, and not a single packet was lost.

EdgeFlow uses the cable automatically: if two Macs can reach each other over a network cable – connected directly or through a switch or router on the same network – EdgeFlow picks that route by itself. You don't need to change anything. In the menu bar, EdgeFlow shows for each connected Mac which route it is currently using.

A cable also helps where wireless isn't allowed at all: some companies prohibit wireless connections between personal and company devices. With a cable, EdgeFlow still works. On company networks, however, automatic device discovery may be restricted by IT (for example by isolating devices from each other) – check with your IT department if in doubt.

Does your Mac have an Ethernet port?

Many Macs no longer have a network port:

• Mac mini, Mac Studio and Mac Pro have a built-in Ethernet port.
• iMac: depending on the configuration, the Ethernet port sits on the power adapter. Check your power adapter – if there's no port, you need an adapter.
• MacBook Air and MacBook Pro have no Ethernet port. An adapter for the USB-C or Thunderbolt port solves this.

The right adapter

An Ethernet adapter simply plugs into a free USB-C or Thunderbolt port and connects to a network cable. In the Apple Store you can get, for example, the Belkin USB-C to 2.5 Gb Ethernet Adapter. If you want to connect several devices anyway, you'll also find docks and multiport adapters with a built-in Ethernet port among the Mac accessories in the Apple Store.

Any adapter that macOS recognises as a network interface works for EdgeFlow – the amount of data for mouse and keyboard is tiny, so the adapter's maximum speed doesn't matter.

Step by step

1. Plug an adapter into every Mac without its own Ethernet port.
2. Connect all Macs to the same router or switch with a network cable. You can also connect two Macs directly with one cable.
3. In System Settings → Network, check that the Ethernet connection (or the adapter) shows as connected.
4. Keep Wi-Fi turned on on all Macs.
5. Check EdgeFlow's menu bar menu: it shows for each Mac that it is connected via cable. EdgeFlow switches to the cable by itself as soon as it is available.

Conclusion

Wireless is the most convenient way to use EdgeFlow: no cable, no shared Wi-Fi, no setup. Most of the time you won't notice any difference from a mouse plugged in directly. Because the direct connection shares the radio with normal Wi-Fi, though, the pointer can occasionally stall for a moment. A fixed router channel without DFS makes this less frequent. If you want a perfectly smooth mouse – for precise work in graphics or video editing apps, for example – connect your Macs by cable and add an Ethernet adapter to your MacBooks. EdgeFlow detects the cable automatically.