I have ER605 in several locations.

They are connected site-to-site to one ER605.

A to B
C to B
D to B
etc.
 

Main "B" is stuck in a Disconnected/Adopting loop. 
 

I am sending logs for viewing. 

While writing this topic, after a few hours the router was up and running for 20 minutes now. The only thing I did was turn off VPN on A C D. I don't know if this has anything to do with it.

For now the router is working, so I'll leave it that way. But the logs may be useful for support to check whether there are any errors in the software.