Thanks for your post.
Let us help you get up and running. We understand that you are experiencing an issue with all channels on your Roku Ultra. Let's try to troubleshoot your device and see if there's any difference after. Have you tried to restart your device? You can use the following steps to restart it from the Settings menu.
- Press Home on your Roku remote
- Scroll and select Settings
- Select System
- Select Power. If you do not see a Power submenu, skip to the next step.
- Select System restart
Once done, we recommend verifying the quality and stability of your network connection as this could be a potential factor contributing to the issue. You can access and review the results of the most recent connection check by visiting Settings > Network > About.
You may also refer to this link: How to resolve a channel playback issue
If the issue you are still experiencing the issue, can you please provide the serial number of your Roku device from Settings>System>About?
Keep us posted and we'll be able to assist you further.