Just to add, I am having the same exact issue on 4.6.4 connecting to a Starlink.
The MT3000 is disconnecting the Ethernet connection for some reason even though the Starlink is not dropping out. Sometimes MT3000 will re-connect, and sometimes it does not and shows "Connecting..." forever. If I unplug the Ethernet cable from MT3000 and plug it back in things will work again for a while.....
I have downgraded back to 4.5.16 as I think this is a firmware bug. I suggest you try the same and see if the issue goes away. I was running 4.5.16 for months with no issues, so I think this is a firmware issue with 4.6.4.
Also have issue open: MT3000, Firmware 4.6.4 and Starlink - Technical Support for Routers - GL.iNet (gl-inet.com)