Facing great problem since I bought the P9. Been an M5 user for many many years with no problem. 

Intermittent connectivity, disconnecting and speed issues. 

on Sep 21 19:56:09 2020 daemon.notice nrd[26657]: wlanifBSteerEventsHandleNodeAssociatedInd: Node 2E:E3:98:D8:47:DF associated on APId 255 ChanId 10  ESSId 1  , Capabilities: BTM RRM  , Max bandwidth: 0, Num of spatial streams: 2, PHY mode: 8, Max MCS: 15. Max TX power: 21
Mon Sep 21 19:56:09 2020 daemon.err client_mgmt: wireless client associate or disassociate.
Mon Sep 21 19:56:09 2020 daemon.err client_mgmt: client_mac:2E-E3-98-D8-47-DF, client_ifname:ath01, client_action:associate
Mon Sep 21 19:56:09 2020 daemon.err client_mgmt: client(2E-E3-98-D8-47-DF) assocaite by if(ath01).
Mon Sep 21 19:56:09 2020 daemon.notice nrd[26657]: wlanifLinkEventsCmnGenerateDisassocEvent: Client 2E:E3:98:D8:47:DF disassociated on APId 255 ChanId 44  ESSId 1  
Mon Sep 21 19:56:09 2020 daemon.info hostapd: ath11: STA 2e:e3:98:d8:47:df IEEE 802.11: disassociated
Mon Sep 21 19:56:09 2020 daemon.err client_mgmt: wireless client associate or disassociate.
Mon Sep 21 19:56:09 2020 daemon.err client_mgmt: client_mac:2E-E3-98-D8-47-DF, client_ifname:ath11, client_action:disassociate
Mon Sep 21 19:56:09 2020 daemon.err client_mgmt: client(2E-E3-98-D8-47-DF) disassocaite by if(ath11).
Mon Sep 21 19:56:09 2020 authpriv.info dropbear[7442]: Child connection from 192.168.8.138:50084
Mon Sep 21 19:56:09 2020 daemon.err /usr/bin/apsd: apsd_get_active_ports:214: Error: No such interface 25
Mon Sep 21 19:56:10 2020 daemon.err /usr/bin/apsd: apsd_get_active_ports:214: Error: No such interface 25
Mon Sep 21 19:56:12 2020 daemon.notice nrd[26657]: wlanifLinkEventsCmnGenerateDisassocEvent: Client 00:D0:2D:59:4D:CD disassociated on APId 255 ChanId 10  ESSId 0  
Mon Sep 21 19:56:12 2020 daemon.info hostapd: ath0: STA 00:d0:2d:59:4d:cd IEEE 802.11: disassociated
Mon Sep 21 19:56:12 2020 daemon.info hostapd: ath0: STA 00:d0:2d:59:4d:cd IEEE 802.11: associated

As you can see 

CPU usage 100% !!!!

My network topology is as follows : 3 X Internet à TP-Link Safestream Multi WAN VPN Router (TL-R600VPN) à Cisco SG350-52 Managed Switch (SG350-52-K9-NA) à Ethernet Deco P9 Main Deco à Ethernet backhaul Salve decos P9 & P7 & M5

Wifi connection is unstable. If you are in the main deco zone internet speed is Excellent. Once I go to some other zones the net speed is very bad 1 or 2 MBps compared to over 170MBps. I tried changing the Main deco to P7 still the same problem. Please note at the beginning I had an IP conflict problem and tried to fix it. Please advise how to solve this problem of speed and fallout + how to setup IP addesses to avoid any conflict. Please note speed issues and dropout was happening even before I installed the Multi wan router and the cisco managed switch.