Telekom Glasfaser with Zyxel SFP ONT
I have Deutsche Telekom’s fiber service running to my home. The standard Glasfasermodem works fine, but I wanted to use an SFP module instead — plug the fiber directly into my switch, eliminate an extra device and its power supply. The good news: it’s straightforward.
First step was finding a compatible SFP module. Deutsche Telekom offers this option to business customers, and the hardware is easy to find on the secondary market. Several people have documented their setups online.
Deutsche Telekom Glasfaser Modem 2, showing the Modem ID on the back.
I settled on the Zyxel PMG3000-D20B, also branded as “Digitalisierungsbox Glasfaser Modem”. You can find it on eBay for about 50€. It supports speeds up to 2.5G and works with most networking hardware. However, compatibility varies, so check your hardware documentation. For example, my Aruba Instant On 1960 had no issues, but some Unifi models reported packet loss.
After talking to customer support, I learned that Deutsche Telekom registers the “Modem ID” (PLOAM ID/SLID) in their backend, and only one modem can be active at a time. Rather than having them register a new ID, I copied the ID from my original modem to the Zyxel module — this way I can always revert if needed.
The SFP module is actually a full Linux machine running OpenWRT. Connect via SSH to 10.10.1.1 with username admin and password admin. Once logged in, set the PLOAM ID (e.g., SCOM0AB1C2D3) like this:
Either command might fail, but the ID should stick. You can also verify this via the Web GUI.
Once you have set it up and plugged in the fiber, onu ploamsg should return curr_state=5 (indicating a successful connection).
Finally, dial-in via PPPoE. For Deutsche Telekom connections, remember to use VLAN 7.
Useful Resources
- A very nice guide that details most of these steps too. You can even use their script to set the ID.
- Detailed information, including hardware pics for the Zyxel PMG3000-D20B (and a lot of other modules too).
- An Edgerouter setup that uses a different authentication method. Note that with Deutsche Telekom FTTH > v1.7, you no longer need the “Installationskennung”.