Wake on LAN not detecting PC is online even though it can be pinged from HA server

I have been using 4 or 5 WoL sensors in HA for several years now and they’ve worked flawlessly. However one of the sensors stopped reliably detecting if the PC is on sometime in the last few months. I think it was somewhere in the Jan to March updates this year but not entirely sure. It will often show the PC is off even when it’s on.

My first troublshooting step was of course to try pinging the PC from the HA server. It’s pingable, so I have no idea why the WoL integration thinks it’s turned off.

As soon as I reboot the HA server it starts detecting it as online again.There is nothing in the logs to indicate any issues with WoL or this sensor as far as I can see. All the other WoL switches work fine and accurately detect if the other PCs are on or not, it’s only this single switch / PC that has the issue.

Anyone else experienced this or have suggestions?

Is it a Windows pc?

If so try temporarily disabling Windows Firewall.

Already checked and no dice. Firewall is off and same behavior. HA host (Pi4) can ping it but the WoL switch thinks it’s off… until I reboot HA then it sees it’s on.

This wouldn’t be as strange if the behavior was universal across all WoL switches but it’s only that one PC. Which I realize makes it seem like it’s a connectivity / network issue with just that PC but since the ping works and rebooting HA fixes it…

Oxxx PC is currently on just the the Lxxx PC

traceroute looks the same for working and non working PCs.

[core-ssh ~]$ traceroute # Working PC
traceroute to (, 30 hops max, 46 byte packets
 1  home-assistant.local.hass.io (  0.058 ms  0.022 ms  0.013 ms
 2 (  0.158 ms  *  0.277 ms

[core-ssh ~]$ traceroute # non-working O... PC
traceroute to (, 30 hops max, 46 byte packets
 1  home-assistant.local.hass.io (  0.019 ms  0.009 ms  0.008 ms
 2 (  0.271 ms  *  0.397 ms