So I woke up this morning to discover that our internet had gone down sometime during the night.  I figured it was a simple matter of restarting either my phone or my router, but it's turning out to be more complicated than that.

For background we have Spark Fibre 100, and it's been pretty reliable for the past 6 years.  We have a Edgerouter 4, and a Unifi AP for wifi.

On our one ethernet connected PC, I've tried a restart, but it still shows as "no internet."  However, I've got successful ping results from 8.8.8.8.

I restarted my phone (Galaxy Note 8) and turned off mobile data.  I got intermittent/slow connections, but some apps won't connect to the internet at all.  Currently, I can't connect to the internet at all on my phone.

On our Fire TV (on wifi), it seems to be working fine.  I can access Netflix, Youtube, and it's working normally.

On our second Fire TV (ethernet) it's also working fine.  As above, I can access Netflix, Youtube no problems.

I've tried restarting the router (no change), power-cycled the ONT (no change), and restarted all non-working devices (no change or inconsistent connections).

This strongly suggests to me that the internet connection is fine, but that something is going on in my home network.  I didn't make any changes recently, so I can't think of anything to roll back.  Any suggestions?