What is error code (-2) for Home Pod set up?

I have a three year old HomePod.  “ios18.5” broke several timers associated with my HomeKit automations.  It was pointed out that the timer issue was attributed to my HomePod hub.  I removed the HomePod and subsequently tried to re-install it.  However, every attempt ended with: "Setup failed. (-2)". No one at Apple can tell me what the “-2” error code refers to.  HomePod setup actually fails after wifi network connection has been established.  Somewhere in the "Apple account setup", the configuration stops with the above error code "-2".  Subsequent HomePod “18.5” update applied, but problem still exists.  Apple Support worked with me till they said I needed to visit Apple Store Genius bar.  They actually set the HomePod up on their network, so, it must be something on my network.  But what?  No one can tell me specifically what error code means.  Like I said previously, from my Unifi UDM-P router, I see the HomePod network connection fully established and communicating until I get the HP setup failure. Then the connection drops. The key question here is what exactly is error code “(-2)”?