I spent quite a bit of time tonight with my ac87u working between 57, 58, and 59.
There is something common between 57 and 59 that absolutely makes my 87u go completely nuts.
By "nuts" I mean:
1) WAN port going dead 3-4 times per MINUTE (red WAN led on the 87u)
2) Wireless clients dropping and rejoining every 1-3 minutes
3) Router completely hangs and restarts (log shows some variable innocuous message, and then you see the time sync drop and a clean restart)
My environment consists of the devices listed at the end of this post plus another 13 or 14 not connected at the time I took the network map export. The problems I describe span 2.4 and 5.8 devices. Most noticeable are my Surface 3 and my S7 Edge because they're in my hand most of the time but most devices experience the issues when on .57 or .58.
.58 is absolutely stable
There has to be something common to .57 and .59 that this particular 87u cannot deal with.
I'm hoping the Luma mesh wifi I just pre-ordered is more stable and reliable. I've had every Asus since the 66- two 68's and this 87, but I'm about done with it. I just pray the Luma has the flexibility to support dozens of forwarded ports for my internal devices with DNS addresses.
Chromecast (Security Cameras)
MyQ Garagedoor
Ring Chime
Chromecast (Master Bedroom)
Watchdog
Insteon Hub (Pro)
S7 Edge
-NAS1
Tab A
Kindle Fire HDX
Chromecast (Media Room)
_Tablet
_Server
Harmony Hub (Great Room)
Chromecast (Great Room)
SecCam7-Front Bedroom
Seccam6-Driveway 2
SecCam2-Fron
SecCam3-Driveway
Seccam4-Front of House
SecCam5-Garage
Wink Hub
Smarthings Hub
Note 4
HP Photosmart 7520 (Office)
Side Yard Camera Outlet
Moto360 (2015-Gold)
Moto360 (2014-Black)
S6 Edge
Insteon Hub (Std)
Great-Room-TV
Game Room Bridge
Harmony Hub (Media Room)
Great Room Photo Frame
Thermostat (Great Room)
Alexa Dot (Great Room)
Surface Pro 3
Panasonic Blu-ray (Media Room)
Front Camera Power Outlet
Thermostat (upstairs)
Hue Hub
Front Camera Power Outlet
Alexa Echo (Master Bedroom)
Kitchen Refrigerator
Thermostat (Dining Room)
-Computer
_Server Power Outlet