back to article LG's $1,300 5K monitor foiled by Wi-Fi: Screens go blank near hotspots

LG's space-age monitors are suffering from an engineering flaw that causes the screen to become unusable when placed too close to a Wi-Fi hotspot. Owners of the top-end displays writing on Apple's reviews page say they have found that, when placed within two metres of a router or wireless access point, an UltraFine 5K monitor …

  1. Anonymous Coward
    Anonymous Coward

    Did someone not do their EMC/FCC/CE testing then?

    Or is it just that it needs the special kind of emissions you can only get from a Mac user:

    "can even cause the connected Macs to freeze, requiring a restart." (? what's freezing here: the screen, the Mac, both?)

    1. RichardBarrell

      Re: Did someone not do their EMC/FCC/CE testing then?

      > "can even cause the connected Macs to freeze, requiring a restart." (? what's freezing here: the screen, the Mac, both?)

      At a guess, it could be something like: the monitor goes faulty and repeatedly attaches and detaches from the display output on the Mac's video card; the Mac has to change the window manager & video card state when a monitor is attached or detached; the rapid toggling tickles a bug in the video driver or window manager, leading it to freeze; and you don't normally experience that bug because it's not normal to be able to repeatedly plug and unplug a monitor that quickly without a hardware fault.

      Or maybe when the monitor's bugged it does something amusing like sending totally bogus EDID information that tickles a bug somewhere. "I have a width of -3200 pixels and I want to be driven at 4MHz" or something equally silly.

      Given the complete uselessness of faulty hardware, bugs which only occur when you have faulty hardware plugged in aren't top of the priority list to fix. It's pretty reasonable that a problem like that could be left lying around for years.

      1. patrickstar

        Re: Did someone not do their EMC/FCC/CE testing then?

        I don't know how screen locking works on MacOS, but if it's as horribly stupid as X then a bug that would let you crash the foreground application would let you bypass the screen lock. So a bug that lets you do that by plugging in various forms of broken hardware would be security critical.

        No idea if that applies here though as only hangs are mentioned, but it could very well be a sign the relevant code should be looked over.

    2. Aitor 1

      Re: Did someone not do their EMC/FCC/CE testing then?

      Almost nobody tests their stuff as they claim. This is normal with "self regulation/self certification": it means wild west.

      It is also fun than Macs freeze, as they obviously also did not test for interference.

      1. Dan 55 Silver badge

        Re: Did someone not do their EMC/FCC/CE testing then?

        The Macs are probably freezing because they're connected to a monitor that's going mental.

      2. Lord Elpuss Silver badge

        Re: Did someone not do their EMC/FCC/CE testing then?

        "It is also fun than Macs freeze, as they obviously also did not test for interference."

        You win the prize for random conclusion of the day. If Macs didn't test for interference they would likely also be subject to freezes and restarts when close to a router regardless of whether they're connected to LG's monitor or not.

        As the poster above eloquently articulates, it's far more likely that the monitor is freezing, sending scrambled or corrupted information back down the signal line and tickling a bug in the video driver; but rather than state that that is 'obviously' the case, I would simply say that somebody needs to do a proper fault analysis on this and identify the root cause, rather than jumping to conclusions.

    3. Mark #255

      Re: Did someone not do their EMC/FCC/CE testing then?

      Amusingly* the immunity standards for IT equipment stop at 1 GHz for radiated immunity tests (which are harmonised in Europe and give a "presumption of conformity to the essential requirements").

      That being said, even if your immunity tests do cover the Wi-Fi ranges, it'll generally be at 1V/m. If your Wi-Fi router is at full power, anything closer than ~4ft will be illuminated at more than 1 V/m. So there shouldn't strictly be any expectation of satisfactory operation.

      * for some value of "amusing".

  2. LaeMing

    They're holding it wrong?

    1. Steve Evans

      i think you mean they're looking at it wrong.

  3. David Pearce

    Emissions get tested, immunity is often skipped, because it costs far more

  4. Tessier-Ashpool


    I have one sitting about 30cm from an Airport Express router. Not so much as a single flicker. I guess some routers are noisier than others.

    1. tony2heads

      Re: YMMV

      The problem maybe caused by something that is not supposed to be there, like some harmonic or intermodulation product in the RF signal.

    2. R 11

      Re: YMMV

      Or, if you read the article, you'd note that some users were able to mitigate by changing WiFi channel. It's possible that you could get a new neighbor who has a router blasting on the channel you're currently using. You might change you channel (or the airport could do it automagically if it's smart enough) and discover a problem - possibly after the warranty period expires.

  5. Dan 55 Silver badge

    Apple have found someone who do even less testing than themselves

    That hatchet job to the Apple ecosystem is working out so well. Now they're held hostage to the likes of LG.

  6. DropBear

    Let me guess - does it have fancy modern touch controls (including the on/off switch)...? You know, the kind that operates on the spooky action at a distance known as electric fields, not entirely unlike the voodoo-machines that give us our WiFi...?

    1. Anonymous Coward
      Anonymous Coward

      sounds like the bank of 3 asus monitors in front of me now, if there is any local transmission on 439 mhz the control panel goes nuts and locks up.

      Wouldn't be so bad if I didn't run an amateur radio repeater that transmits on 439 mhz

  7. Dave 126 Silver badge

    "LG's space-age monitors..."

    Isn't any post-CRT monitor 'space age'? Heck, even the Sony Trinitron CRT was only released in 1968, after man in had been in space and not long before man set foot on the moon.

    So, let's have some suggestions for a phrase to replace 'space-age'. Please leave them below!

    Mars age?

    Reusable rocket age?

    Twitbook age?

    1. Julz

      Re: "LG's space-age monitors..."

      Internet age.

      1. Inventor of the Marmite Laser Silver badge

        Re: "LG's space-age monitors..."


    2. allthecoolshortnamesweretaken

      Re: "LG's space-age monitors..."

      Pre-WW III-age.

    3. Harvey Trowell

      Re: "LG's space-age monitors..."

      Hold the Front Page Trump is on a Ramp Age

      Major Boob Age

      Hornby Da Blogue Age

      Bruce Hornsby and the Range


      What was the question?

      1. Dave 126 Silver badge

        Re: "LG's space-age monitors..."

        "These are the days of miracle and wonder

        This is a long distance call

        The way the camera follows us in slo-mo

        The way we look to a star

        The way we look to a distant constellation

        That's dying in a corner of the sky

        These are the days of miracle and wonder

        And don't cry baby, don't cry"

        - From an album that begins with a description of an Improvised Explosive Device. It was a slow day...

  8. Wyrdness

    A simple solution would be to put your router in a faraday cage

  9. Stuart Castle Silver badge

    Social Media Age?

    Mind you, that could apply to any product that you buy, feel tempted to brag about online, then post photos of, sitting next to your dinner on Instagram/facebook/twitter etc.

    1. Inventor of the Marmite Laser Silver badge

      Covered already:


  10. Missing Semicolon Silver badge

    Many monitors suffer

    from mobile phone signals.

    I have two recent ones (one LG, one Viewsonic) which blank when my phone is too close.

    The elderly Dell next to the VS seems unperturbed....

  11. toughluck


    Thanks for that tip!

    I have an LG 34UM88C and it has exactly the same problem (I have my access point underneath my desk, directly beneath the monitor). If I shuffle in my chair, or as much as anyone goes by the room, it goes blank for a second or so.

    It only happens on the HDMI connection, I noticed no problems with DisplayPort. Strangely, though, this is my second unit (the first one was replaced due to a panel fault) and I never noticed that on the first unit.

    1. Mystereed

      Re: Yes!

      I remember in the days of CRT monitors when someone had their screen replaced because the picture used to wobble.

      The new one started to do the same after a short time - they had put their electric fan back next to it again after moving it away for a while when the replacement was put in.


      1. Anonymous South African Coward

        Re: Yes!

        Wibbly wobbly here comes Mr Jelly! :)

  12. Anonymous Coward
    Anonymous Coward

    Are the display's corners sufficiently rounded?

    And is it thin enough?

  13. Cynic_999

    This is not a design fault

    As has been pointed out, a WiFi hotspot close to the monitor will be subjecting it to RF fields of a frequency and intensity outside the requirements of the present EMI immunity standards. Therefore unless the design specifications explicitly stated that it must be capable of operating next to a WiFi router, it is not the fault of the design engineer. Nor would I expect any testing process to include every conceivable mix of equipment that the device might be used with. This is the reason why mobile phones and other RF emitting devices are not permitted to be used on an aircraft (nowadays relaxed to be only during critical flight phases). Not because anyone believes that they WILL interfere with aircraft systems, but because the aircraft systems have not been tested or certified to operate with a mix of strong RF fields at random positions and frequencies within the aircraft, and so MIGHT be affected.

    You can however bet your socks on the fact that not only LG but many other manufacturers will be adding the requirement to their design specs from now on.

    Meanwhile the solution is pretty simple - move the WiFi hotspot. You'll probably even get better WiFi coverage when it's not being blocked by a large monitor ...

    1. David Pearce

      Re: This is not a design fault

      IEC-61000-4-3 2006 introduced immunity testing to 6 GHz, jumping from 2.5 to cover 5.8 GHz WiFi

      1. Mark #255

        Re: This is not a design fault

        IEC-61000-4-3 2006 [...]

        That's merely a basic standard, containing the test method. It doesn't require testing to be undertaken over the entire frequency range. The product standard for IT equipment is CISPR 24, which calls up IEC 61000-4-3, but only specifies its use up to 1 GHz.

        And yes, I am an EMC engineer.

  14. Alistair Silver badge

    Interference issues.

    I've had to explain to an elderly fellow that the reason his laptop was utterly unreliable had to do with the fact that it sat on top of the generator housing for the log splitter. (I've heard about efficiencies etc, but it was a wacky setup). There was less than 1/4" of steel and less than 1' of clearance between the outer stator housing and the laptop. It would regularly mangle files, fail to boot, require a complete rebuild. Very likely didn't help that used power from the same source. It was the third complete rebuild I asked *exactly* where he was using it.

    That said, that generator put out a *hell* of a lot more RF interference than anything folks are going to have hanging around their house making wifi.

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