Same problem here with all my iOS devices. One of my friend also has a note 2 and exactly the same thing happens that you mentioned in point 1 with the 87u. Have perfect connection but can't seem to surf the net or check email, etc. happens at least twice a day on each device on the 5ghz band using the latest firmware with the updated driver (3754).
Running latest firmware from this thread for my 87R and installed the day it came out and did two factory resets on New Year's Day and as of today experiencing intermittent issues all day for the first time.. I have charter (DHCP is normal not aggressive) and contacted charter twice where each time they confirmed no issues with Modem or neighborhood regarding speed. I have two iMac's hard wired one is used for work and seen in my logs an unholy amount of miniupnpd closed Unexpectantly (I shutdown my non work computer and cleared logs without thinking so don't have full transcript) issues. Most of the issue in the logs were resulting from the non work iMac but also a few from the work iMac.
Will edit post when I see the error again.
Issue just happened today for over three hours as of 325 est where on my 60download connection I've seen
ing as high as 4,000MS and a DL speed of .029 it's progressively getting better after a restart of modem and router however still intermittent. Charter is convinced it's on my end and I disagreed until I seen my log firing off miniupnpd errors almost every two minutes or so.
This also affected two iPhone 6 Pluses, an iPad Air 2, and the two mentioned iMac's. I will also note about a week after latest beta came out I started experiencing the issue where 5ghz would stop and I'd have to throw my devices into airplane mode temporarily to fix but I've been dealing with that however the other issue is job impacting.
Here's the error that was spamming my logs like crazy:
Jan 11 15:16:27 miniupnpd[733]: HTTP Connection from 192.XXX.X.XXX closed unexpectedly
This is happening every 15 minutes on Work computer, non work computer is remaining offline until work shift is over.
Jan 11 15:16:27 miniupnpd[733]: HTTP Connection from 192.XXX.X.XXX closed unexpectedly
Jan 11 15:31:27 miniupnpd[733]: HTTP Connection from 192.XXX.X.XXX closed unexpectedly
Jan 11 15:46:27 miniupnpd[733]: HTTP Connection from 192.XXX.X.XXX closed unexpectedly
Router firmware: 378.3754
Edit at 1630-ish started noticeably going down again on wifi and hard wired devices:
Jan 11 15:16:27 miniupnpd[733]: HTTP Connection from 192.XXX.X.XXX closed unexpectedly
Jan 11 15:31:27 miniupnpd[733]: HTTP Connection from 192.XXX.X.XXX closed unexpectedly
Jan 11 15:46:27 miniupnpd[733]: HTTP Connection from 192.XXX.X.XXX closed unexpectedly
Jan 11 15:49:37 miniupnpd[733]: Expired NAT-PMP mapping port 37370 UDP removed
Jan 11 15:49:37 miniupnpd[733]: Expired NAT-PMP mapping port 37370 TCP removed
Jan 11 15:56:14 kernel: br0: received packet on vlan1 with own address as source address
Jan 11 15:59:57 ntp: start NTP update
Jan 11 16:01:27 miniupnpd[733]: HTTP Connection from 192.XXX.X.XXX closed unexpectedly
Jan 11 16:18:28 kernel: br0: received packet on vlan1 with own address as source address
Jan 11 16:59:59 ntp: start NTP update
Jan 11 17:00:11 ntp: start NTP update
Jan 11 17:00:41 ntp: start NTP update
Jan 11 17:00:45 ntp: start NTP update
Jan 11 17:00:48 ntp: start NTP update
Jan 11 17:00:52 ntp: start NTP update
Jan 11 17:00:59 ntp: start NTP update
Jan 11 17:01:28 miniupnpd[733]: HTTP Connection from 192.XXX.X.XXX closed unexpectedly
Jan 11 17:06:32 miniupnpd[733]: Expired NAT-PMP mapping port 16403 UDP removed
Jan 11 17:06:34 miniupnpd[733]: Expired NAT-PMP mapping port 5900 TCP removed
Jan 11 17:06:36 miniupnpd[733]: Expired NAT-PMP mapping port 4500 UDP removed
All 192.XXX.X.XXX reflects the same IP above
One final note I have three routers total, the 87R, 68U running the just released ASUS firmware and N66U with latest Merlin Release.
87R is directly connected to my Modem and the 87R connects a wired bridge to my N66U and another wired bridge to my 68U.
The work computer is connected via cat6e to my Wired N66U which is cat6e wired to my 87R.
My 87R and 68U both share the same SSID's and WPA2 pass keys but each band is on a separate channel (87R's 2.4 is on different channel then my 68U's 2.4 band and etc..)
The reasons for my layout shouldn't matter as much as how they are laid out so being detailed and also wanted to note all cabling in my setup is utilizing cat6e cable.