AVH-W4400NEX Android Auto intermittent connection issues - familiar? HW or FW?

[jeffw_00]

Hi - I have a 4-year-old AVH-W4400NEX that I've been using with Samsung phones (S9, S21, S23) for Android Auto.  All worked perfectly until recently.  Now, intermittently, the phone either has trouble connecting to Android Auto, or loses the connection.  On initial connect, it gets to the black screen which you typically see quickly before AA comes up, but it stays there for 15 sec or so and then reverts to the 4400 screen.  (During that 15 sec, the phone says (in notifications).  "Android Auto is available on your car screen".,   Or, it connects, and then after a bit it will disconnect with "Android Auto disconnected".   Sometimes it will connect but then say something like "when the car is stopped, check your phone to continue using Android Auto" while the phone says (in notifications).  "to continue using Android Auto, refer to your car screen".  

All this happens on either of our two phones (S21 or S23).    Hard reset (poking the pin in the hole) or power-reset (disconnect from battery) didn't help.  I'm running V1.02.   Resetting the phone or ignition-cycling the car often fixes it temporarily but it comes back.   Clearing the pairing and re-pairing also didn't help. 

I tried going back to using wired, but it gets more frequent.  and even worse if I don't turn off the WiFi before trying to use wired. 

I'm trying to decide whether it is FW (in which case a new SD Card may fix it) or HW (in which case it's time to buy a new unit). 

Anyone seen this or have ideas how to debug it?

Thanks!
/j