Installed the FW v. 1.10 07 downloaded on 9/23/2016 and am experiencing WiFi drops and reconnects on all android mobile devices, happening roughly once every two minutes or so. WiFi disconnects on Roku and Nvidia Shield (which uses Google android TV over its own OS) also happen, but not as frequently, perhaps because those do not move around the house. Windows PCs seem to be the most stable, but my current work has me at my wired tower rig instead of my WiFi laptop. Wired connections are stable. Turning SC off helps some, but not completely.
My first impression was that SC was being overzealous in trying to move each device to the very, very, very, super-very best connection it could possible find for that device, and doing it by using machine logic, meaning a straight Boolean algorithm of "if better connection exists then change channel, count 60 seconds, repeat; else repeat" along with a similar instruction for band. (Yeah I know, I made that up and I do not program firmware, but it's not the point). But that would not explain why it also happens when SC is turned off, unless there is something similar that is used under all circumstances. Or most likely of all, it has absolutely nothing to do with my wild and uninformed hypo-guess-thesizing.
As FYI if it's even remotely useful: DIR-890L is attached directly to an up-to-date DOCIS Motorola modem, and there are three direct wired connections from the router to different NAS devices, and one wired connection to a switch. The switch is connected to cables in the walls; one of the wall connections goes to a DAP-1650 AC AP, one to another switch, and one to my tower rig. Not that it should matter, but there is another DAP-1650 closer to the router that is set up as a media bridge using an AC wireless connection. Mobile devices include three android phones, an android tablet, and an iPad, plus the Shield and Roku devices.All OS's are kept up to date. For what it's worth, throughput using Speedtest.net averages 94 MBPS download, and 11.6 Mbps upload, at least when it's connected (Cox cable).
Can't think of anything else I might be able to add that might be useful in some way, and know that what I did put up here is pretty unlikely to be useful either.
As for me, I'm now going back to 1.09.
I wish D-link speed and good luck in getting this resolved.
Peter K.