I initially had the same problem with instability. My big mistake was assuing I could load my AXE11000 settings into the AXE16000. It worked but it turned out to be the source of all my instability. I have a 5 router mesh. I currently have the AXE11000 as a wired mesh node and the 16000 is the primary.
I Reset all my routers to factory default. installed my 16000 as the primary then added in the mesh nodes . Everything has been great for the last couple months.
New firmware today, 50168. After the firmware upgrade, I got a message about entering the password incorrectly 5 times. Since I had not tried to enter a password, you might see if you get the same message.
After a period of time, I was able to log on normally.