The above is still happening to me with the node firmware updated to 20287.
Its really strange. It seems to cause the AIMesh to fail when this is happening (Aimesh does reconnect eventually). I'm going to try turning off AiMesh and see if that fixes it. If that fails, then I'll try going back to the 1900p as my main.
Turning off AIMesh fixed this. I tried the scenario multiple times with AiMesh turned off and didn't have the issue.
Added AiMesh RT-AC1900p back to the RT-AC86U and started happening again. I didn't see anything unusual in the syslog but here is the chain of events. Also, this only seems to be happening when "sleeping PC2" via RDP, rather than the power button. It only seems to happen when AiMesh is on and it seems to make the AiMesh node offline when it happens.
*** Resume from Sleep PC2 by pressing power button
Jan 29 09:41:41 kernel: eth4 (Ext switch port: 3) (Logical Port: 11) Link UP 1000 mbps full duplex
*** Connected to PC2 from PC1 over RDP.
Jan 29 09:41:49 kernel: net_ratelimit: 6187 callbacks suppressed
Jan 29 09:41:54 kernel: net_ratelimit: 14881 callbacks suppressed
*** Sleep PC2 from PC1 over RDP
Jan 29 09:42:27 kernel: eth4 (Ext switch port: 3) (Logical Port: 11) Link DOWN.
*** No network access on PC1 (Lan or WAN)
Jan 29 09:42:27 kernel: net_ratelimit: 885 callbacks suppressed
Jan 29 09:42:32 kernel: net_ratelimit: 20287 callbacks suppressed
Jan 29 09:42:37 kernel: net_ratelimit: 11681 callbacks suppressed
Jan 29 09:42:42 kernel: net_ratelimit: 8476 callbacks suppressed
Jan 29 09:42:47 kernel: net_ratelimit: 7898 callbacks suppressed
Jan 29 09:42:52 kernel: net_ratelimit: 6483 callbacks suppressed
Jan 29 09:42:57 kernel: net_ratelimit: 6433 callbacks suppressed
Jan 29 09:43:02 kernel: net_ratelimit: 4979 callbacks suppressed
Jan 29 09:43:07 kernel: net_ratelimit: 5137 callbacks suppressed
*** Resume from Sleep PC2 by pressing Power button
Jan 29 09:43:10 kernel: eth4 (Ext switch port: 3) (Logical Port: 11) Link UP 1000 mbps full duplex
*** PC1 now has network access
Jan 29 09:43:12 kernel: net_ratelimit: 6162 callbacks suppressed
*** Sleep PC2 using power button
Jan 29 09:43:38 kernel: eth4 (Ext switch port: 3) (Logical Port: 11) Link DOWN.
*** PC1 continues to have network access.
Jan 29 09:43:38 kernel: net_ratelimit: 499 callbacks suppressed
Jan 29 09:43:43 kernel: net_ratelimit: 14365 callbacks suppressed
Jan 29 09:43:48 kernel: net_ratelimit: 10137 callbacks suppressed