UniFi

UniFi Dream Machine and Telekom Fiber

It finally happened: I replaced my DSL uplink with fibre optics from Deutsche Telekom. Although I had been using my UniFi Dream Machine together with a Draytek Vigor for years, I wanted to optimize things a little further by using an SFP module instead of an external modem. After some research, I settled on a Conbic PMG3000-D20B-C, which seemed to be what others had been using as well. While the module had been delivered weeks ago, I had to wait until yesterday for the GT-TA to be set up by Deutsche Telekom. And then I ran into two minor problems… Failing Connection Test To activate everything, Deutsche Telekom has this nice wizard-style process. It asks you for the ID printed on the GT-TA and the serial number of the modem, then tells you to disconnect your existing DSL cable and so on. I ran through that process multiple times, and the system always complained that the modem was offline. From my side of things, everything looked mostly fine: the SFP module was seated properly and showed a green LED. What made me somewhat nervous was the fact that UniFi was reporting “Faulty SFP EEPROM”. Calling the hotline did not help much either because my setup is not really the sweet spot. With a little bit of luck I realized that I had been doing this incorrectly the whole time. Apparently, two different types of modem ID are common: 12-bit and 16-bit. The modem has two serial numbers printed on it: one is a 12-bit number starting with XPON, and the other is the so-called GPON SN, which is 16-bit. Interestingly, the UniFi UI shows the 12-bit number as the device’s serial number, which made me use that one half a dozen times. It is the wrong one. The modem ID needed at this point was the GPON SN, which reminds me a lot of a MAC address. Once I used the correct modem ID, I was able to successfully finish the connection test. PPPoE Not Working As I was switching from VDSL with the Draytek, my Dream Machine was already properly configured: VLAN 7 and PPPoE were set up correctly. Yet when I switched the port for the internet connection, the Dream Machine failed to connect to the internet. I found the culprit while I was talking to the Telekom hotline, almost by accident. While trying to find a solution to the first problem, I had played around with the link negotiation settings for the SFP module, switching from “Auto Negotiation” to “1Gbe Full Duplex”. I have not figured out why this causes problems, but with “Auto Negotiation” enabled again the link speed still reports as 1Gbe. Manually configuring it that way appears to break PPPoE in my case. In other words, do not play with the link negotiation here. Open Questions I believe the Conbic PMG3000 has a web UI that can also be used for firmware updates. I have not found a way to reach it yet. If anybody has an idea, please let me know.