I spend 1½ day on this issue including 5 calls to the YouSee support. I’m sharing this solution so that you hopefully don't have to.
I've had a Netgear 6250 COAX modem for multiple years. It has always been running in Bridge-Mode. And it has been running just fine. Bridge-Mode is none-negotiable for me. I have ZyXEL firewall and router connected to the Modem.
In February, I started to get fall-outs. The connection would drop every 2-10 days. Not sure why. I eventually contacted Yousee support and they suggested that I reset the modem. And so I did, upon which an even worse world-of-pain descended upon me.
I never got the Netgear modem up and running again and eventually Yousee swapped it for a SagemCom 3890 modem. I was happy for a short while, until it became clear that I was unable to get this to work either! I couldn't understand why, as this set-up had been working for years.
Eventually I did manage to get things up and running. My resolution was as follows:
1. Reset the modem. Press and hold the small white button for approx. 10 seconds. It’s found on the bottom of SagemCom Modem.
2. Wait for the modem to reboot. It will take a while.
3. Connect a PC to the Modem via Ethernet (probably must be a PC, you’ll see why later). IMPORTANT: Don’t connect anything else to the modem until this guide tells you to!
4. Log-in to the administrative web-console of the Modem using ip: 192.168.0.1. The username is admin and the password is on the paper slip you got with the modem. You still have it, right? If not, call support.
5. Find the setting where you can change from Router-Mode to Bridge-Mode. It’s easy to find if you are just a little bit technical and understand router fundamentals and if you don’t then neither Bridge-Mode nor this guide is for you, in which case call some it guy to help you out.
6. Disconnect the PC. Nothing should be connected to the Modem at this point.
7. Now the Modem will reboot again and now things begin to become interesting…
8. Find the MAC address of the WAN interface on your router (NOT the modem, your router!).
9. Change the MAC-address of the PC you are using, to the MAC-address of your router’s WAN interface – i.e. the MAC-address to noted down in step 8. You might want to note the MAC-address of the PC network card before you change it. You will need to revert the PC network card to its original MAC-address at a later point. If you don’t the PC and the router will no longer get along on your network. (Hint: I tried to change the MAC-address on an Apple Macbook Pro. I failed, which is why I’m using a PC. On a PC, changing the MAC-address was a breeze).
10. Connect the PC to the Modem and open a browser. As you do this, this web-page will likely come up: https://aktiver.mitwifi.dk/. If it doesn’t come up automatically, then browse to it. If you can’t browse to it then this guide will be of no help to you. In that case call support and good luck with that by the way.
11. Follow the simple guide at https://aktiver.mitwifi.dk/
12. Wait for the Modem to reboot. Leave the PC connected!
13. When the modem is running again, your PC should have access to the internet.
Also, note down the ip-address that the PC have now been given.
14. Disconnect the PC. Change back the MAC-address on the PC to its original value. This is important!
15. Connect the router to the Modem. The router will now automatically ask for a WAN ip-address and it should now be given the very same ip-address that the PC have just been given. Why? Because the PC was “impersonating” the router by using its MAC address. This was the trick!
16. You’re done and hopefully your router should work from here on.
You might not need all of this, but I did. If I didn’t impersonate the router on the PC, the PC would be handed the right ip-address, not the router. In fact, the router would try to get an ip-address too, but was given an address in the 10.138.14.0/16 range. However, this other range will not give you access to the internet and you and your router would get stuck in no-mans-land. I tried to explain this to the support to no avail. I could even ping their router at 10.138.14.1 indicating quite clearly that I had a connection all the way to a subnet in their network, but that argument didn’t get me anywhere.
I also tried to initiate https://aktiver.mitwifi.dk/ from the LAN via the router, but that was not possible. The PC had to be directly connected to the modem. Not sure why.
I tried to explain many time to the support that there seemed to be an issue in their end. They were always nice to begin with, but eventually they would fall back to “ohhh but we don’t support bridge-mode so there is nothing else we can do”, which pretty much drove me crazy. It would have expected to get to 2nd level support at that point, but that didn’t happen.
So why did my set-up stop working in the first place? My assessment is two reasons:
1. The Netgear modem broke after years of steady use. When I looked in the log, the log showed log entries from January 1st, 1970??? This seems to indicate that the small battery in the modem keeping the time right at power-lose, had probably stopped working. This was probably also why it has started to fail. But there is no way to be sure.
2. Yousee must have changed their process for handing out ip-address for set-up's using Bridge-Mode. The changes might have been implemented a long time ago, but since my router have not asked for an all new ip-address for a long time, my Netgear router had hummed alone just nicely renewing the already assigned ip-address until the point in time when I reset it and it had to ask for an all-new ip.
I hope this guide will help others.