My WANs at all loactions have been upgraded to SuperVectoring with Profile 35b which includes Technicolor DGA4130 Router than can do Bridge mode (apparently openwrt built in), my 3900 does not get connection confirmation, this seems to be an issue with how the DGA4130 Communicates back to confirm PPPoE is in affect....

My other locations have VigorBX2000ac which are using DGA4130 in bridge Via WAN-2 ethernet port and works fine ( 262MB down and 22Mb up )

This same issue happens also for my Ubiquiti USG-Pro-4 , both it and the 3900 PPPoE sents out the connection logins etc , the DGA4130 connects all green lights but they don't see its connected

pppd(18625): Unable to complete PPPoE Discovery
pppd(18625): PPPoE session recieve error ??? stop waitForPADO...
pppd(18625): error recieving pppoe packet: network is down