Please if you find out why 2,4G that slow let us know, have same problem with 86U and no solution since months (there is no old firmware for 86U which works).
Drivers and everything updated downgraded, tried everything, still very very slow, after turn off/on maybe faster at beginning and not usable after time.
Here is what i found, I've moved off almost all of devices from the 2.4ghz ssid that has the issue. So far changing the 2.4 ghz settings doesn't make a difference, but this is the only thing that showed up in the debug logs right before the problem reoccurred right around 22:09 to 22:15 and kernel: br0: received packet on eth1 with own address as source address. Wireless speed on 2.4ghz went to less than 1mb/s. It's also very strange how many dhcp requests and acknowledgements are in the logs. Almost like a layer 2 broadcast storm.
May 18 20:20:33 kernel: nvram: consolidating space!
May 18 20:48:06 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.128 d0:52:a8:35:83:1e
May 18 20:48:06 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.128 d0:52:a8:35:83:1e st-D052A835887A0001
May 18 20:58:20 dnsmasq-dhcp[376]: DHCPDISCOVER(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 20:58:20 dnsmasq-dhcp[376]: DHCPOFFER(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 20:58:20 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 20:58:20 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 20:58:30 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 20:58:30 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 20:59:41 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 20:59:41 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 21:01:02 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 21:01:02 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 21:02:48 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 21:02:48 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 21:04:00 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 21:04:00 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 21:05:43 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 21:05:43 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 21:06:40 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 21:06:40 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 21:06:58 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 21:06:58 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 21:18:42 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 21:18:42 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 21:22:12 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 21:22:12 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 21:46:58 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 21:46:58 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 21:49:46 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 21:49:46 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 22:09:33 kernel: br0: received packet on eth1 with own address as source address
May 18 22:09:34 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.200 44:85:00:11:29:02
May 18 22:09:34 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.200 44:85:00:11:29:02 LenovoYoga2
May 18 22:09:46 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 22:09:46 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 22:12:43 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 22:12:43 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 22:14:12 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 22:14:12 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 22:15:24 kernel: br0: received packet on eth1 with own address as source address
May 18 22:15:24 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.200 44:85:00:11:29:02
May 18 22:15:24 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.200 44:85:00:11:29:02 LenovoYoga2
May 18 22:15:49 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 22:15:49 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 22:15:57 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 22:15:57 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 22:16:41 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 22:16:41 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 22:16:54 dnsmasq-dhcp[376]: DHCPDISCOVER(br0) 7c:7a:91:52:96:a3
May 18 22:16:54 dnsmasq-dhcp[376]: DHCPOFFER(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 22:16:54 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 22:16:54 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 22:18:48 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.200 44:85:00:11:29:02
May 18 22:18:48 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.200 44:85:00:11:29:02 LenovoYoga2
May 18 22:19:53 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 22:19:53 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 22:19:58 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 22:19:58 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 22:20:53 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 22:20:53 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 22:21:14 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 22:21:14 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 22:23:46 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 22:23:46 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 22:24:22 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 22:24:22 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 22:24:49 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 22:24:49 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 22:25:19 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 22:25:19 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 22:25:41 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 22:25:41 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 22:26:19 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 22:26:19 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 22:26:59 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 22:26:59 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 22:27:55 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.167 7c:7a:91:52:96:a3
May 18 22:27:55 dnsmasq-dhcp[376]: DHCPACK(br0) 192.168.1.167 7c:7a:91:52:96:a3 HP1040-LT
May 18 22:29:21 dnsmasq-dhcp[376]: DHCPREQUEST(br0) 192.168.1.200 44:85:00:11:29:02