Electronics giant LG has admitted its new premium-priced computer displays experience "performance issues" when placed near a wi-fi router.
The LG Ultrafine 5K monitor costs almost £900 and is promoted as an external display for Mac devices.
But customers noticed the display flickered or switched off when near a wi-fi router and some posted negative reviews on Apple's website.
LG told the BBC that customers should change the location of their display.
"Monitor arrived today and the picture flickered on or off when using with a brand new Macbook Pro," wrote one reviewer.
Another added: "The device is not properly shielded from wi-fi radiation, so you can't have a wi-fi router within two metres of this display or it will go black.
"Simply not ready for public release."
In a statement, LG apologised for any "inconvenience" customers had experienced.
"Changing the location or positioning of either the router or the display should resolve the issue," it said.
It added that any Ultrafine 5K monitor manufactured from February 2017 would have "enhanced shielding" to protect the devices from electromagnetic interference, while customers experiencing persistent problems should contact LG.