MikeB4:
My Arlo cameras threw a hissy fit. All offline including the Base unit. Tried for a few hours to fix it and have up. Couldn't even factory reset the Base unit. Changed cables, power cycled, restarted entire network without any success.
I had exactly the same experience with my Arlo camera's earlier this year.
Three cameras and the base unit all stopped working at the same time. I tried everything you did, but still nothing.
Replaced with a couple of Wyze unit's I had lying around until I decide what to replace them with next.