Variable Internet Speed on iMac and MacBook Air

Question

Level 1

10 points

Variable Internet Speed on iMac and MacBook Air

I use a 2020 27" iMac (3.3 GHz 6-Core Intel Core i5) and recently purchased 15" MacBook Air (M2 chip) on WiFi. Using both machines in the same room/router, same WiFi network, I get widely different internet speeds from Xfinity. Typically the MacBook Air shows 200-400 Mbps on the Xfinity speed test, whereas the iMac shows 25Mbps or less. Why, surely the speed on both devices should be very similar?

I have tried rebooting the modem, router and switching on/off the WiFi on both machines, no change in speed. Your thoughts would be much appreciated.

Posted on Oct 29, 2023 9:51 AM

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Answer 1

Tesserax

Level 10

157,800 points

Oct 29, 2023 12:59 PM in response to mgattmch

Please provide a screenshot of the Wi-Fi menu from each Mac.

To get the full statistics, hold down the option key before selecting the Wi-Fi icon on the macOS menu bar. Either provide the following info, or provide the screenshots.

Security =
Channel =
RSSI =
Noise =
Tx Rate =
PHY Mode =
MCS Index =
NSS =

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Answer 2

Oct 29, 2023 11:44 AM in response to mgattmch

To get the true speed Comcast is supplying, connect your Mac directly to the modem via an Ethernet cable. You may need an Ethernet dongle/adapter.

This will eliminate the router and Macs as variables and give you talking points with Comcast.

You'll need to monitor the speed for several days. Use Comcast's speed test to determine the speeds.

If you get a Comcast tech out, this is what they will do, so give yourself a little ammunition ahead of any tech visit.

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Answer 3

Ronasara

Level 6

15,519 points

Oct 29, 2023 10:33 AM in response to mgattmch

Since it is occurring on both Macs, I agree that Xfinity is the likely issue. There are are some apps out there which allow you to test your carrier's speed. Speediest.net is one place to go. I believe I saw a test link on Comcast's web site. I would do multiple tests and record the speeds. Then contact Comcast and see if they can offer a solution.

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