@Marvin_S 

1. The previous firmware version

1.1.1 was the pervious version, and then I upgraded to the beta build.

2.How did you make two Archer BE800 work? As Easymesh ethernet backhaul is a new added function from 1.1.1 version.  Did you connect 2 BE800 via Easymesh wireless backhaul? Or ser second BE800 as AP mode?

I'm using Ethernet Backhaul on 1.1.1 and then on the beta build.

3.What does "routers crashes" mean? Failed to access the internet wirelessly?  Does it happen on both BE800? Can BE800 obtain IP address?

Anytime anyone says anything about a router crashing, it means it stops working, restarts.  Like a power cycle but something causes the router to stop working and it restarts itself.  At one point it crashed about 5 times in one afternoon.

4.Whenthe issue happens, if you acess the Tether APP via mobile data istead of wifi connection, can you log into the Tether app and manage BE800?

I can, yes.  What's not acceptable is the number of times it crashes since upgrading to 1.1.1 or the Beta build.

5. When the issue happens, what is the status od LED on the main BE800? Can you log into the web interface to check the Internet status? Can you export system log and share us?

I'll see if i can pull one.