Looks like the incompetent coders at Asus firmware dept cannot code a stable built even after 1 year of beta testing.
My GT-AX6000 with 3.0.0.6.102 built has serious issues to get 2nd VLAN to work and the UI gets highly unstable if you change few settings quickly. The whole router comes to a grinding halt with random settings turning on by themselves like TTL settings on WAN page. The only solution is to reset the router again to get it back to working state and change settings very slowly. But if settings stick and router is still working after all settings change, then it can run stable for weeks.