Hello,

Same issue occurs to me.

I've got a 3-unit kit of DECO P9 with the following firmware version:

1.1.0 Build 20200513 Rel. 52023

Mi network topology is:

ONT ----{PPPoE}--- Main DECO P9 (Router) ----- [DECO P9 Slave / DECO P9 Slave] 

Randomly I'm suffering disconnection issues on several devices. Investigating the last issue on a windows 10 laptop, connected by wifi, in the network manager it appears "No internet connection": I had to disconnect from my wifi network and re-connect again restore the network access to internet.

During the lapse of time of the issue I've observed the following logs in the page (some entries have been edited):

Mon Jul 13 09:00:30 2020 daemon.err udhcpd[5342]: clear ip c0*****
Mon Jul 13 09:05:25 2020 daemon.err udhcpd[5342]: Sending ACK to 192.168.1.XXX 
Mon Jul 13 09:05:25 2020 daemon.err udhcpd[5342]: clear ip c0*****
Mon Jul 13 09:08:16 2020 daemon.err udhcpd[5342]: Sending ACK to 192.168.1.YYY
Mon Jul 13 09:08:16 2020 daemon.err udhcpd[5342]: clear ip c0*****
Mon Jul 13 09:09:01 2020 daemon.err udhcpd[5342]: Sending ACK to 192.168.1.ZZZ
Mon Jul 13 09:09:01 2020 daemon.err udhcpd[5342]: clear ip c0*****
Mon Jul 13 09:09:26 2020 daemon.err client_mgmt: wireless client associate or disassociate.
Mon Jul 13 09:09:26 2020 daemon.err client_mgmt: client_mac:B4-D5-XX-XX-XX-XX, client_ifname:ath1, client_action:disassociate
Mon Jul 13 09:09:26 2020 daemon.err client_mgmt: client(B4-D5-XX-XX-XX-X) disassocaite by if(ath1).

Note: On the above log the IP marked as 192.168.1.XXX is my inner laptop IP and B4-D5-XX-XX-XX-XX is my laptop MAC address, obfuscated for security reasons.

Regards

@mcr 

Same problem here after upgrading to 1.1.0 Build 20200513 Rel. 52023. I've tried 30-30-30 reset, swapping the Main between all three Deco P9 units and nothing helps. The problems happens daily. Sometimes several times in an hour. Online chat with TPLink hasn't yet proven helpful. Prior to this firmware upgrade, I had zero disconnections. I found several threads on this site with similar problems but based on the timeframe for this firware update, I fear this regression defect will take a very long time to be resolved!