By "NLA", do you mean Network Level Authentication? I thought that was just for use with RDP?
Alternatively, are you referring to the list of previously connected networks that Win10 stores in HKLM\SOFTWARE\Microsoft\WindowsNT\CurrentVersion\NetworkList\Profiles\[...]? Embarrassed to admit I hadn't thought to check that, but I will. I suppose it's possible that the "BN16.com" connection could be a hangover from the configuration process that my laptop's manufacturer might have run on it. I will take a look a post my findings here.
In terms of tweaking the behaviour or presentation of these Avast Firewall settings in future: it was quite alarming to see a set of new networks appear in the firewall settings menu. It may help reassure Avast users who are a little too security-conscious (such as myself) if the firewall only displayed networks that it was involved in managing. For most users this would mean that Avast only listed the network they were using at the time Avast was installed, and any network that the "toaster"/pop-up prompted them to set to private or public afterward.
That sounds like ignorance is bliss. I've always opted for more information not less just because less would make me feel better.
