I recently switched from my beloved MacBook Pro Retina (Late 2013) i5 2.6/16/512 to MacBook Pro (2017) Non-TB i5 2.3/16/512.

I purchased what from the build-quality looked like a good USB-C-to-DisplayPort cable with 4k/60Hz support, just to run into the very problem the Logicboard repair guru Louis Rossmann had described in one of his videos: As soon as you plug in the USB-C dongle, the (2.4 GHz) Wifi stops working despite full antenna signal. Unplug the USB-C connector and you are immediately back in the game.

The big question I'm asking myself now: Who is to blame? Is this a design flaw in the current generation MacBooks with improper shielding or is it a design flaw in the various dongles?

I mean the fact that even Apple’s very own USB-C Digital AV Multiport Adapter is causing these WiFi issues (as you can learn from the many horrific customer reviews; but AFAIK have been fixed through a software patch), show that there’s something going horribly wrong.

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One customer got a good USB-C Hub and after plugged it to their MacBook Pro then appears the same wifi interference problem.

He solved the interference by covering the Hub with aluminum paper

(Thanks Faraday!)

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  • A better shielded cable can also work. Not sure that's an option with this dongle though. – Wayfaring Stranger Oct 27 '19 at 19:23
  • Thanks, I felt like I'm losing my mind. How do I check for properly shielded cables on my next dongle buy? – David Schumann Apr 24 at 11:48

Blame physics. The inverse square power law means that a signal that is very weak a few feet away can cause severe interference right next to the Bluetooth and WiFi disrupting the 2.4 GHz signal.

Now, if the Mac works without any accessories, you have to blame the accessory or purchaser of the accessory of you insist on a blame centric worldview. For most people, understanding that interference can happen helps them find practical remedies.

Great shielding can help as can drivers that literally turn off the USB 3.0 signal periodically to give the WiFi a better (slim) chance to get some traffic through.

Unless you can somehow separate the devices physically, even with ideal 2.4 GHz radio conditions of low noise and good signal, with properly designed, properly assembled and correctly operating USB 3.x hardware, they can interfere significantly with the older WiFi standard channels in the 2.4 GHz range.

If you use a lot of the newer adapters, you'll want to be sure you have a good 5 GHz wireless network running. You'll also need a way to measure / triage / eliminate faulty or poorly designed USB 3 devices - they will ruin many people's day with interference.

The good news is the power of the good devices is low and the inverse power law prevents a USB 3.0 device from interfering with 2.4 GHz signal across the room, but for the computer connected, they are simply too close in most cases to rely on both 2.4 GHz WiFi and USB 3 together.

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  • 5
    Now explain that to the average "housewife"... USB-C was supposed to simplify things drastically (one connector for everything), but the horrifying fact is that it is a sheer chaos, which you and me are able to decrypt, but the common user can't: • USB-C cables, which basically look the same, but have drastically different Wattage ratings (think Smartphone vs. Notebook charging) or drastically different transfer rates (standard USB-C vs. Thunderbolt 3 cable) • USB-C cables/adapters causing Wifi interferences (as described above) • etc. – Dr. Woo Jul 12 '18 at 17:59
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    I wouldn't blame physics because they can't change the "inverse square power law" (there isn't such a freedom in this universe, we will have to upgrade it 😊). I would rather blame all actors working in the field of radiofrequencies and not taking enough time to check they won't kill the communication of any other product on the market by emitting at too high a power. – dan Feb 16 '19 at 12:40
  • My wifi gets killed immediately and at random. And i mean killed, not interfered. Full signal, zero connection, working at full speed a moment before. It resume just after I unplug the hub. Does not seem an interference to me. – Marek Maurizio Sep 10 '19 at 10:57

Got my Ugreen type-c adapter works with extension cable! External hdmi display, usb 3.0 hdd and mouse are works fine! No problem with wi-fi or bluetooth. adapter connection with extension cable

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    I was thinking on going to buy a large extension cable but then I saw answer below and I covered my adapter with aluminum paper and It just worked perfect!! – Oswaldo May 4 '19 at 14:20
  • @vash_st tell me please, what kind of cable it is? is it screened? Does it have a brand? Can you confirm that this solution works without problems? – Maxim Uvarov Dec 19 '19 at 12:57
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    Hi Maxim, I ordered this one a.aliexpress.ru/QMDzCx0 Honestly I didn't used it much time as mostly my MBP is used separately. But when I used it worked fine for me. – Vash_St Dec 23 '19 at 21:19

I was having this same issue but was able to come up with a work around. By using google speed test and having one cable plugged in at a time, I was able to determine that my front right USB port was the problem. If I have it plugged into my usb hub or monitor from that port, my wifi takes a turn for the worse. (Note: the wifi source is located on the right of the computer, so maybe it would be the left side if your wifi source is located on the left of the computer.)

Luckily, I noticed the issue does not persist if the power cable usb-c is plugged into that port. So, I just have my ports arranged so that my power usb-c is always plugged into the front right port.

For testing it, go to google speed test. And as the test is running, place and remove your hand over your ports. For me, I could clearly see that change of speed if my hand covered the ports. Find a cable that causes a problem, and then test each port individually. Hopefully, the problem is not as bad in some of the ports. If so, then use the ports where it works well, and for the bad port or ports, use it for the usb-c power cable only. Good luck!

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    Welcome to Ask Different! :) I hope you come to find this site has a lot to offer! In case you haven't already, it's worth taking the time to read the tour. All the best! – Monomeeth Dec 16 '18 at 4:41

Like @bmike have stated.. blame physics.

What gave me the solution was the fact that at the office everything worked just fine, and at home I had problems..

my solution was to raise my Macbook 5-10 cm above the adapter.. seems to have work wonders on the wifi connectivity and stability!!

Fight physics with physics...

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I have a 2018 Macbook pro. As soon as i plug anything into USB C I completely lose my wifi. I recognized that the noise is in 2.4 GHZ from the usbc cable which is the same frequency as the wifi. I went on Amazon and purchased. Ferrite chokes. I attached on on my usbc cable as close to the end as I could. Now I can hook up my second monitor without any wifi issues. this was a bad design flaw on the part of Apple.

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  • +1 for answer and idea. I have 2019 Macbook Pro and having the same problem - while I was on 2.4G my wifi completely stopped work (strange fact: not always, just sometimes, without known pattern). I reconnect to 5G and it works like a charm. But this is not a solution! It looks like that a lot of extra accessories are not built as it should be (with all frequency tests, cable shields, electromagnetic interferences, etc.). – Puzo Jan 31 at 20:32

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Foil Wrap works!!! No more slow wifi and dropping network connection after wrapping 2 hdmi multiport dongles.

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  • Welcome to Ask Different! Please refrain from adding comments in the Answer section, this is for answers to the questions. Once you have sufficient reputation you’ll be able to add comments and ask follow-up questions. To gain reputation, answer questions that are clear and concise. - From Review – fsb Feb 7 at 14:23
  • The most useful answer IMO. – stevec Apr 28 at 11:03

It seems to be a problem, that doesn't get a lot of attention as "people should simply use 5 Ghz wifi networks". For anyone with a 2.4 Ghz network:

Intel has released a white paper on the topic of "USB 3.0* Radio Frequency Interference Impact on 2.4 GHz Wireless Devices".

ON page 14 and 15 you can see that shielding the cable and partially shielding the body of the connector/dongle helps reduce the noise immensely.

To quote the papers summary:

The noise generated due to the USB 3.0 data spectrum can have an impact on radio receivers whose antenna is placed close to a USB 3.0 device and/or USB 3.0connector. The noise is a broadband noise that cannot be filtered out, since it falls within the band of operation of the wireless device (2.4–2.5 GHz). The noise degrades the signal-to-noise ratio that the wireless receiver sees and limits its sensitivity. This then reduces the operating wireless range of the device.

Improving the shielding on the USB 3.0 receptacle connector can help reduce the amount of noise radiated due to USB 3.0 signaling. In addition, shielding of the USB 3.0 peripheral device plays an important role in reducing the amount of noise radiated in the 2.4–2.5 GHz range. This is particularly critical for peripheral devices that are placed close to the PC platform, such as a flash drive. Placement of the wireless antenna should also be carefully considered on a platform and be located as far away as possible from a USB 3.0 connector and/or device.

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