I have been using my Eero 6 3 unit wifi/router with Comcast without issue.  I have had a great deal of problems with Comcast for the last 5 months.  Just purchased CenturyLink 100Mbps internet, the fastest in my area available.  I can't get the Eero to work with the CenturyLink C4000BG modem.  Does anyone use this combination?  Any help would be much appreciated!