I just had something really weird with this soft. All of a sudden 7 unknowns devices have appeared then disappeared. They all had their Mac at 00:00:00:00:00 which is really disturbing.
I tried to ping the IP given by Soft Guard but apparently nothing was found.
And now it's 32 unknown devices that have appeared.
Is it a bug ? Or something really bad is happening in the neighbourhood ?
I had the exact same symptoms, and it appears that the vpn connection (along with a remote desktop link) I had running was the culprit. The IP addresses didn't make sense with regards to the vpn connection i.e. not in the same subnet, but they were in the range of my home network. It also seems that the bogus addresses were not pingable by me.
Perhaps a coincidence, but so far it appears that the issue is corrected.