The 2.5Gigabit fiber modem that Deutsch Telekom sells needs a PPPoE connection, even with a subscription like Company Pro. Here’s a little how-to for testing the connection to it on Ubuntu, before trying to get it working with a third party router.

After connecting and registering the modem, I plugged it into my laptop. It has the IP Address 192.168.100.1, so statically configure your laptop to e.g. 192.168.100.2 and connect to it to look at the web interface.

The modem requires a PPPoE connection with VLAN tag 7 to work. Most older routers are unable to provide the VLAN tagging, so they won’t work. Despite other infos on the internet, enabling EasyConnect on the Magenta portal, still requires a correct username/password for the connection.

See Telekom NetworkManager setup for the set-up I successfully used on my Ubuntu laptop to test the connection. I tried before to set up the connections using the Gnome NM UI, but was unable to establish the connection.

Here are the commands that worked. enx22e04ca4a742 is my USB ethernet interface. Network Manager will append .7 to it, but needs to truncate by two letters to attain to the maximum length. REPLACEME is the Personliches Kennwort that belongs to the Zugangsnummer. The username is of the format:

AnschlusskennungZugangsnummer#Mitbenutzernummer@telekom.de.

$ nmcli connection add type vlan vlan.parent enx22e04ca4a742 vlan.id 7 ipv4.method disabled ipv6.method ignore connection.autoconnect no
$ nmcli connection up vlan # Use tab to complete and choose the right
$ ip addr | grep ‘.7’ # Read the new interface name
$ nmcli connection add type pppoe username 002234098466551239265619#0001@t-online.de password REPLACEME ifname ppp1 pppoe.parent enx22e04ca4a7.7
$ nmcli connection up pppoe-ppp1 # Use tab to complete

Now you should see the following in the logs:

$ sudo journalctl -n 200 -f -u NetworkManager
PAP authentication succeeded
peer from calling number CC:E1:7F:AD:9C:FE authorized
nm-ppp-plugin: status 8 / phase ‘network’
PAP authentication succeeded
peer from calling number CC:E1:7F:AD:9C:FE authorized
local  IP address 80.153.148.32
remote IP address 62.156.244.30
primary   DNS address 217.237.149.205
secondary DNS address 217.237.151.51