why cant i play halo 4 online with other players

What error message are you getting when you try to play online?

Hello Donald,

Adding onto what our ambassador Jenkins has provided, you also follow our
Xbox One networking connection solution support article for reference on more steps involving your home network.

Try what has been provided and let us know the results.

Best wishes!

Adding onto what everyone else has said, it could also be an issue with your ISP. I know i have had issues with games like halo and call of duty. I find if you set your ip address to a static ip adress you end up with better results. You may have to reset
occassionally but it gets you results.

Please check your NAT type on your console. If you have a "Strict" type it could be preventing you from joining other players or hearing them.

Here are the steps to check your NAT Type:

1. Open the guide by pressing the Xbox button in the center of your controller.
2. Scroll right in the guide to the System area
3. Select Settings.
4. Select Network.
5. Select Network Settings.
6. Select Test NAT Type

Have you played other games than just Halo 4? Halo 4 has had a problem with connectivity due to so many players online. They are fixing it. It's due to the high demand of their servers for so many players.