There problem with DSL/pppoe in 18.04 flavors:
DSL/pppoe connection doesn’t work: I create it, but instead of it autoethernet appear.
BUT! Somehow there no such problem in Kubuntu.
I just tried Ubuntu Mate and there AutoEtherent appears instead of what I’ve created.
But there was pppoeconf. Strnge: UM has it, usual Ubuntu has it, but not in Xubuntu.
Did you select the “Automatically connect to this network when it is available” in the “General” tab? If selected, it will connect whether it appears in the applet or not.
Yeah, that works. Thanks.
Glad to help… 
Kindly mark that reply as the solution if it solved your problem, that way if anybody else faces the same thing, he/she will find the solution quickly…