LG messed up royally with the launch of its UltraFine 5K display. The 5K IPS screen, which is exclusively sold via the the online Apple Store, lacks functional EM shielding and suffers from numerous major issues.
Due to the lack of proper shielding, the display can exhibit weird behavior when other electronics like a router are nearby. For example, the screen can flicker or go totally black, and some customers even report kernel crashes on the host machine.
As ARS Technica reports, LG recommends users of the UltraFine 5K to place routers "at least 2 meters away" from the monitor:
A support rep for LG Electronics confirmed that the 5K monitor can be adversely affected by a nearby wireless router and said that the issue doesn't affect any other LG monitors. Hall was asked to place the router "at least 2 metres away" from the monitor and "to let us know" if the problem still persists after that.
If you take a look at the monitor's product page on the Apple website, customer reviews started pouring in from January 25; a few of them are positive, but a lot of them are negative. Some of them explicitly call out the router-proximity issue, but many other major issues are also described: kernel panics on the host machine, random flickering even when there are apparently no nearby sources of wireless radiation, and USB devices not being reliably detected when plugged into the monitor.
The UltraFine 5K display is currently sold for $974 via the Apple Store, down from its $1,299.95 introduction price. It was widely seen as the new MacBook Pro display because Apple isn't making its own 5K display.