Recently bought Dlink DIR-882 and updated it to recent firmware (HW:A1, FW:1.01).
In portal disabled SmartConnect and configured 5GHz only (custom SSID, WPA2, 802.11 ac only, auto channel, visible) - this worked fantastic for first two days.
Later, 5GHz SSID just disappeared, no iphone7 or Ipad can see it.
Enabling the 2.4GHz (different SSID) working without an issue.
I've tried several things: factory defaults, no security, single mode N, forcing channel to 48/149 - nothing helped, just can't see 5GHz SSID, not discoverable.
Don't have other 2.4Ghz or 5Ghz cordless phones or WiFi APs,
Really out of ideas what to test next.