I have Eero 6 plus system with 3 nodes.  Installed recently and very happy with the system.  We live in a fire-prone area and have a lot of power outages from PG&E.  We had one today.  We have a whole house standby generator and the Eero gateway node is plugged into a USP battery backup.  The power went out today and within seconds the generator was on and all power restored.  But the fiber Internet was down.  Thinking it was my ISP I called them and they said everything was okay on their end.  Checked local Facebook and others had Internet.  I recycled my ISP modem and then recycled the Eero gateway node.  Nothing worked.  Limping through the Internet I found other people that had experienced this problem and I took bits and pieces from each to finally resolve my problem.

I had to disconnect all of the nodes from power.  I unplugged two CAT6 cables coming into the ethernet ports on the gateway node.  With everything unplugged I plugged in the CAT6 cable from the modem into the gateway and then powered up the gateway node.  Let it run and initialize and finally it turned solid white and I had an Internet connection.  I then plugged in my other two nodes and they also initialized.  I had to log back in to a couple of devices, but everything else came back online.  I thought I would post this just in case someone else ran into the same problem. Just powering off and on of the gateway node did not work.  Had to unplug everything and start kind of like the initial install.  I can't imagine why this would happen with the Eero system.  The Netgear router I replaced with the Eero system has gone through dozens of power outages and always booted right back up with only the interruption time it takes to boot.  I see this as a problem if a power outage occurs when no-one is home; Internet will be lost and critical things like security cameras and wifi sprinkler systems will not function.  

If anybody has a solution on how to prevent this Eero system down from a power outage and generator restart of power, please let me know.  Thank you.