Solved: VLAN How to do pppoE with ISP "Deutsche Telekom" using ifname ppp1 pppoe.parent enp3s0.7
Post scriptum: using nmcli, VLAN works just fine.
While DD-WRT firmware for a WRT54GL router as well as roaring-penguinPPPoE Linux-x86-driver have zero problems with VLAN ID 7 tagging during pppoE to DTAG (Telekom) ISP in Germany, NetworkManager or some affiliated component makes it hard to impossible to go online with a recent VDSL2 line in Germany as customer of Telekom AG. It used to work well with prior DTAG systems not requiring VLAN 7 tag, but now for some time, unless the customer's system do VLAN tagging to 7 there is no pppoE and the customer stays offline with modem-only-mode (as opposed to router mode of the IAD (such as "Smart 2") which comes with lots of closed source shenanigans).
So NetworkManager must be able to fully support VLAN tag 7 just like rp-pppoE has been doing for decades.
I tried with nmcli scripts and all, watched the console error output, but there seems to be a NM problem.
pppoe-discovery
works nicely etc. so I believe I narrowed down the issue to NM. Any ideas?
Does anybody have a bash-script with nmcli instructions which actually work against a Deutsche Telekom 100 MBit VDSL line via pppoE-passthrough? I could not google much for this standard task.
I can give more scripts, screenshots asf. to reproduce if this report seems odd. Does anybody use VLAN in a real world task? Given that the GUI in KDE clearly has issues, that may be a rare use case.
Here, the pppoE connection just always fails to connect since it cannot use the enp3s0.7 device as rp-pppoE can. And with enp3s0 there is no connect neither. roaring penguin worked intuitively & flawless on the first try and did so ever after, except it is quite slow and old kinda unmaintained software.