@TP-Link
checking the logs after today's test it's clearly obvious, ARP table of the "living room" does not have the client entries connected to another deco. The log entries are from the same time when I did the test walking around the house during the ping test. The ARP error issues pop up, then disappear and pop-up again, when I was near the living room deco:
ed Nov 3 15:02:12 2021 daemon.err client_mgmt: client(40-A3-CC-1F-54-28) not found in arp table disconnect_counter=0
Wed Nov 3 15:02:12 2021 daemon.err client_mgmt: client(94-B9-7E-E0-3E-24) not found in arp table disconnect_counter=0
Wed Nov 3 15:02:16 2021 daemon.err udhcpd[6280]: Sending ACK to 192.168.68.139
Wed Nov 3 15:02:16 2021 daemon.err udhcpd[6280]: clear ip 8b44a8c0
Wed Nov 3 15:02:32 2021 daemon.err client_mgmt: client(40-A3-CC-1F-54-28) not found in arp table disconnect_counter=1
Wed Nov 3 15:02:41 2021 user.warn IMPROXY: WARNING[mcast_recv_igmp@753]: Don't exist this Downstream VIF
Wed Nov 3 15:02:53 2021 daemon.err client_mgmt: client(40-A3-CC-1F-54-28) not found in arp table disconnect_counter=2
Wed Nov 3 15:02:53 2021 daemon.err udhcpd[6280]: Found static lease: 6b44a8c0
Wed Nov 3 15:02:53 2021 daemon.err udhcpd[6280]: Sending ACK to 192.168.68.107
Wed Nov 3 15:02:53 2021 daemon.err udhcpd[6280]: clear ip 6b44a8c0
Wed Nov 3 15:03:09 2021 daemon.err udhcpd[6280]: Sending ACK to 192.168.68.106
Wed Nov 3 15:03:09 2021 daemon.err udhcpd[6280]: clear ip 6a44a8c0
Wed Nov 3 15:03:35 2021 daemon.err client_mgmt: client(44-73-D6-0D-E2-6C) not found in arp table disconnect_counter=0
Wed Nov 3 15:03:56 2021 daemon.err client_mgmt: client(44-73-D6-0D-E2-6C) not found in arp table disconnect_counter=1
Wed Nov 3 15:04:15 2021 daemon.err client_mgmt: client(3C-71-BF-20-83-D2) not found in arp table disconnect_counter=0
Wed Nov 3 15:04:15 2021 daemon.err client_mgmt: client(44-73-D6-0D-E2-6C) not found in arp table disconnect_counter=2
Wed Nov 3 15:04:15 2021 daemon.err client_mgmt: client(D0-3F-AA-5C-E9-AC) not found in arp table disconnect_counter=0
Wed Nov 3 15:04:36 2021 daemon.err client_mgmt: client(40-A3-CC-1F-54-28) not found in arp table disconnect_counter=0
Wed Nov 3 15:04:37 2021 daemon.err udhcpd[6280]: Found static lease: 7444a8c0
Wed Nov 3 15:04:37 2021 daemon.err udhcpd[6280]: Sending ACK to 192.168.68.116
Wed Nov 3 15:04:38 2021 daemon.err udhcpd[6280]: clear ip 7444a8c0
Wed Nov 3 15:04:40 2021 daemon.err udhcpd[6280]: Sending ACK to 192.168.68.125
Wed Nov 3 15:04:40 2021 daemon.err udhcpd[6280]: clear ip 7d44a8c0
Wed Nov 3 15:04:46 2021 user.warn IMPROXY: WARNING[mcast_recv_igmp@753]: Don't exist this Downstream VIF
Wed Nov 3 15:04:56 2021 daemon.err client_mgmt: client(40-A3-CC-1F-54-28) not found in arp table disconnect_counter=1
Wed Nov 3 15:04:56 2021 daemon.err client_mgmt: client(34-7E-5C-37-99-6C) not found in arp table disconnect_counter=0
Wed Nov 3 15:05:16 2021 daemon.err client_mgmt: client(40-A3-CC-1F-54-28) not found in arp table disconnect_counter=2
Wed Nov 3 15:05:17 2021 daemon.err client_mgmt: client(70-A2-B3-E2-E6-1F) not found in arp table disconnect_counter=0
Wed Nov 3 15:05:17 2021 daemon.err client_mgmt: client(34-7E-5C-37-99-6C) not found in arp table disconnect_counter=1
Wed Nov 3 15:05:59 2021 daemon.err udhcpd[6280]: Sending ACK to 192.168.68.151
Wed Nov 3 15:05:59 2021 daemon.err udhcpd[6280]: clear ip 9744a8c0
Wed Nov 3 15:06:43 2021 daemon.err client_mgmt: wireless client associate or disassociate.
Wed Nov 3 15:06:43 2021 daemon.err client_mgmt: client_mac:D0-3F-AA-5C-E9-AC, client_ifname:ath1, client_action:associate
Wed Nov 3 15:06:43 2021 daemon.err client_mgmt: client(D0-3F-AA-5C-E9-AC) assocaite by if(ath1).
Wed Nov 3 15:06:51 2021 user.warn IMPROXY: WARNING[mcast_recv_igmp@753]: Don't exist this Downstream VIF
Wed Nov 3 15:06:57 2021 daemon.err client_mgmt: client(58-D3-49-2D-D2-57) not found in arp table disconnect_counter=0
Wed Nov 3 15:07:06 2021 daemon.err client_mgmt: wireless client associate or disassociate.
Wed Nov 3 15:07:06 2021 daemon.err client_mgmt: client_mac:D0-3F-AA-5C-E9-AC, client_ifname:ath1, client_action:disassociate
Wed Nov 3 15:07:06 2021 daemon.err client_mgmt: client(D0-3F-AA-5C-E9-AC) disassocaite by if(ath1).
Wed Nov 3 15:07:17 2021 daemon.err client_mgmt: client(58-D3-49-2D-D2-57) not found in arp table disconnect_counter=1
Wed Nov 3 15:07:17 2021 daemon.err client_mgmt: client(78-28-CA-84-E0-0E) not found in arp table disconnect_counter=0
Wed Nov 3 15:07:36 2021 daemon.err client_mgmt: client(58-D3-49-2D-D2-57) not found in arp table disconnect_counter=2
Wed Nov 3 15:08:21 2021 authpriv.warn dropbear[20205]: Login attempt for nonexistent user from 192.168.68.139:59215
Wed Nov 3 15:08:37 2021 daemon.err client_mgmt: client(58-D3-49-10-7E-3C) not found in arp table disconnect_counter=0
Wed Nov 3 15:08:56 2021 user.warn IMPROXY: WARNING[mcast_recv_igmp@753]: Don't exist this Downstream VIF
Wed Nov 3 15:08:57 2021 daemon.err client_mgmt: client(3C-71-BF-20-93-5C) not found in arp table disconnect_counter=0
Wed Nov 3 15:08:57 2021 daemon.err client_mgmt: client(58-D3-49-10-7E-3C) not found in arp table disconnect_counter=1
The MAC addresses 40-A3-CC-1F-54-28, 44-73-D6-0D-E2-6C, 3C-71-BF-20-83-D2 belong to the devices which are connected to the "garage deco". So: ethernet backhaul decos and wireless connected decos does not share/keep sync their ARP tables!
If all decos are Wireless backhaul connected or ALL decos are Ethernet backhaul connected, the issue is not visible. If the backhauls are mixed, seems to be the ARP table is not synced correctly. Please check!