strange icmp echo request behaviour

[C.G.B. Spender]

Hi, yesterday I've encountered strange issue: Consider 4 of my computers, each one runs identical version of KIS 20.0.14.1085, let's call them A,B,C and D. For the longest time everything worked as expected, and every one of the four computers could ping any from the remaining 3 without problem. Yesterday I noticed my NMS reports computer A as down. Investigating computer A I couldn't see any issue, it had lan and internet connectivity and could ping B,C,D without issue. No other computer on the local lan could however ping A. After some debugging it turns out it was KIS firewall. What is strange though, all of A,B,C,D have the same default firewall settings of blocking incoming icmp echo requests, despite this B,C,D happily respond to icmp echo requests. To fix my situation, I had to disable the 2 rules blocking the icmp echo on computer A. Machines B,C,D still have them enabled, yet any of the 4 computers can now ping any of the remaining 3. Any idea why is this? With identical settings and non-identical behaviour I have no idea where to look for the true root of the issue (blanket disabling of firewall rules ain't my kind of solution)

[Wesly.Zhang]

Hello,

Does machin A go to sleep mode before? Does this issue occur after system wake up from sleep mode ?

Regards.