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Internet not working after activation: Modem stuck in "Cable internet synchronization starting (training)

  • January 24, 2026
  • 4 Antworten
  • 30 Aufrufe
C
Besucher:in

Hi,

I am writing here because I do not speak German and I am having trouble reaching the technical support.

My O2 Cable internet was supposed to be activated, but I have no connection (I got an email from o2 saying that my internet has been activated). When I check my modem's event log, I see the following error message repeating every few minutes:

"Cable internet synchronization starting (training)"

I have already tried restarting the modem and checking the cable connections, but the problem persists. It seems like the modem cannot establish a stable synchronization with the line.

Could a moderator please check my line status or help me open a technical ticket?

Note: Please let me know what information you need (Customer Number, etc.) and I can provide it via private message.

Thank you in advance for your help.

4 Antworten

schluej
Legende
  • schluej
  • January 24, 2026

Moin Moin,

you could use:

Our english speaking support

We started our english speaking hotline to address your concerns regarding tariffs, ordered hardware or technical difficulties.

If you’re already using the Mein O₂ App, you can now contact our English support hotline directly from the App. You can access the hotline via Service→ O₂ Hotline

The direct route without the app is via the number 089 6666 300 81, our colleagues will gladly assist you. The opening hours are Mon. - Fri. 8 am - 8 pm, Sat. 10 am - 6 pm, on workdays.

If the power/cabel LED is blinking than tell the support.

Live long and prosper 🖖
    o2_Bianca
    • o2_BiancaModeratorin
    • Moderatorin
    • January 24, 2026

    Hey ​@Cgcanpolat,
    thank you for contacting us with your query. Welcome to the o2 Community. schluej has already given you the right advice. Please contact English customer service directly on the number provided here. They will be happy to assist you. Please keep us updated here to let us know if they were able to help you. 
    Kind regards, Bianca

    Schau mal in unserem digitalen Wohnzimmer vorbei. Es lohnt sich https://g.o2.de/community-treffpunkt
    C
    Besucher:in
    • Cgcanpolat
    • Autor
    • Besucher:in
    • January 24, 2026

    Hello,

    Unfortunately, I waited for an hour to connect, only for them to hang up on me. I ordered 1000MBit internet but can’t use it. The worst thing is that there’s no one looking into the issue. Looks like I’ll have to cancel the contract and go to another service provider. 

    o2_Giulia
    • o2_GiuliaModeratorin
    • Moderatorin
    • January 24, 2026

    Hello ​@Cgcanpolat,

    Unfortunately, we cannot create tickets for the technical support service here via the o2 Community.

    You may need to configure the router directly with our technicians. An on-site appointment may need to be scheduled with you.

    Best regards

    Giulia

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