Sophos Firewall reported computer not sending heartbeat signals

Question

Since November an increasing number of endpoints is reported from Central with "Sophos Firewall SN reported computer not sending heartbeat signals" 
 We upgraded our HQ XG from 18.5.4 to 19.0.1 on Nov 12th but the issue started already before as you can see from the screenshots. 
 Before that, we only received this alerts occasionally. Sometimes the message comes multiple times per day for a machine, then a few days no message is created even if the computer is still in use. 
 What is the issue here? 
 Central Region is Central Europe

One Computer:

Qoosh · Answer

I was able to get some additional feedback on this from our team. 
 The decision-making process behind when these alerts are generated will take place entirely on the firewall. Only if network traffic continues to be routed to the firewall without heartbeat traffic periodically, will the alert be generated. 
 Do you know if the NIC on the affected device remains active/communicating on the network while the system is in hibernate mode? What could also help is checking the power saver settings in Device Manager to check if the NIC is configured to stop communicating when the device enters a sleep state. 
 There are a couple of options available from the XG Console which can limit the frequency at which these alerts/events are generated in Sophos Central. I will follow up with you via PM to share these.

emmosophos · Answer

Hello LHerzog, 
 DEV has some binary ready for NC-111152, I would recommend you to open a case with Support, and you can mention about NC-111152, the case would get to GES and they can confirm is your issue matches NC-111152 and install the binary, to see if this resolves your issue. 
 IF you do this, share the Case ID. 
 Regards,

LHerzog · Answer

Hi Qoosh and thanks for your message. 
 The NICs, LAN or WiFi, may be shot down by the OS to save energy. That option is not disabled. 
 As written earlier, it looks to me like the NIC driver does some usless behaviour / dumping something that shows with those Netwtw10 Events every few seconds. That probably wakes the NIC, sends some packets the firewall sees when the heartbeat driver already sent info to the firewall, that the device is now off. 
 After the driver and BIOS updates, the issue has not happened to the computer that was most frequent before. Probably Intel / Fujitsu changed something on the network behaviour in Hibernate. 
 Will continue to monitor the behaviour on our side. 
 Interestingly the events almost stopped completely after Nov 16th.

Sophos Firewall reported computer not sending heartbeat signals

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