Connecting Deco X60 to Fiber ONT (Adtran 411 - Sonic)
Solved - Sharing in case it's helpful to others.
I wanted to upgrade my home network, replacing my Netgear WNDR3700 wireless router with the Deco X60 mesh system.
My ISP is Sonic (in San Francisco) - Sonic has installed an Adtran 411 ONT device (fiber modem).
The ISP does NOT require user/password.
When I connected the Adtran 411 (LAN port) ONT to one of the ports on the X60, the X60 did NOT connect to the internet. I repeated the setup process multiple times.
The IPV4 is correctly configured as Dynamic IP (default setting) - as it should - in order to receive all info (IP address, Gateway, DNS) from the ISP.
It turned out Sonic had to remotely flush the Adtran 411 device's memory as it could not assign a new IP address to the X60. Once they did this very quick and easy operation (after calling Sonic's helpdesk) I was able to successfully connect the X60 using the setup procedure.
Hope this helps.