Roku fixes are sometimes as easy as logging out and then back in.
Another option is to delete the app and install it again.
Please make sure your phone and Roku app are on the same Wifi.
These usually resolve all Roku issues.
Below are a set of instructions from Roku on how to further troubleshoot and update your system:
- Press the Home button on your Roku remote.
- Scroll up or down and select Settings.
- Select System.
- Select System update.
- Select Check Now to manually check for updates.
In the past Roku had an issue with their tech stack that affected many apps worldwide. This affected us as well. You can read about this here: https://comicbook.com/tv-shows/amp/news/roku-fixing-streaming-issues-operating-system-update-affecting-users/
And here is more info for specific Roku hardware devices: https://community.roku.com/t5/Playback-Issues-Audio-Video-Power/OS-10-5-Some-older-Roku-TVs-and-Roku-Ultra-players-are-experiencing-playback-issues-after-update/m-p/741618#M34138