Online services are up and running Call of Duty: Black Ops 2 Status
If you haven't already done so, please try verifying the game cache Verify Game Cache Files (GCF) - How To's - Knowledge Base - Steam Support
You may also want to try the following:
- Reboot your router.
- Restart your system.
- Try using a wired connection in order to sustain the connection quality.
- To help identify if there is an issue with the router or blocked ports, try connecting directly through the modem.
- Check the NAT type. Is it Open, Moderate or Strict?
- Establish a static IP address and port forward.
Here are the port numbers you will need:
Should you have any questions on how to port forward, please contact your ISP or the router manufacturer.
Moving this over to Technical Support Black Ops II Technical Support