You would be best starting your own new topic as one of the problems here is that the OP can’t give us the URL so no one can investigate it.

So if you are able to give a URL that would be best for you as it is something that can be tested. You should also give some information about your network settings, which are typically Home, Work, Public. I have my network connection set to Public which is the strongest setting on my windows network settings. I also have WPA2 as the Wi-Fi Protected Access and I have never had avast give this kind of un/non-secured notice.