Dns issues

I've had issues for almost a week and no one at xfinity seems to understand how to fix this common issue and now I have to wait on a tech.

I've explained it as clear as I can to them. IP lease is for 10.0.x.x range.DNS library however is pulling a 192.0.x.x ip address from a 192.0.x.x DNS. This allows connection to the router, but the issue causes no assigning of a public ip to my household. This restricts browsing to sites that require me to identify myself as well as won't even allow access to log into the xfinity admin site.  I told each tech, the main times ive called in are to change my plan and bc of dns issues...just check the notes...but here we are, still unresolved