I know this is an older thread, but... I was having the sort of the same issue. What I found is that I'm using Sophos UTM as my router, and for some reason it wouldn't update (haven't investigated the cause). The work around for me was to bypass the security appliance and use my basic home wifi. I'm not sure if this will help anyone, but it caused me several hours of frustration and made me a not very happy camper.