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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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    Take the dongle in question and plug it into a different computer (like a Dell or an HP). Depending if the problem remains or disappears, you will have your answer. You also cannot fix RFI issues in software. – Allan Jul 12 '18 at 11:51
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    You don't mention if this dongle is an Apple or Apple-approved dongle. From years of experience with non-Apple dongles and adaptors of many sorts, build quality and operation can be deficient to downright inoperative. Apple's dongle may work if you can't get this dongle to work. – IconDaemon Jul 12 '18 at 13:14
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    „You also cannot fix RFI issues in software“ – Well, obviously you can to a certain extent, as you can see here. Needless to say that one can't create a metal GND shield in software ;) – Dr. Woo Jul 12 '18 at 14:39
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    „You don't mention if this dongle is an Apple or Apple-approved dongle“ – It's a third party dongle, but given to the fact that the interferences even occur using Apple’s very own adapter (as described here above), „Apple approved“ means nothing. (Is there actually such thing as „Apple approval“ when it comes to USB-C dongles? The fact that Apple sells the stuff online or in their stores actually means nothing, but mainly profit-driven – whichever manufacturer matches a certain built-quality standard and is willing to bow low enough). – Dr. Woo Jul 12 '18 at 17:42
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    I have one adapter that works fine on one MBP but fails on the other. Long story short, given the fact that is one of most expensive laptops, I expect to not have this issue. – Robert Gabriel Oct 7 '18 at 18:07
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Blame physics. The inverse square power law means that a signal that is very weak and right next to the antenna will be as loud and prone to interfering with the 2.4 GHz signal.

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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    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. – daniel Azuelos Feb 16 at 12:40
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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

2

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!)

1

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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0

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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TacB0sS is a new contributor to this site. Take care in asking for clarification, commenting, and answering. Check out our Code of Conduct.
0

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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Stefen B is a new contributor to this site. Take care in asking for clarification, commenting, and answering. Check out our Code of Conduct.

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