If you're having issues with Xbox Remote Play, start here:
1) Please follow the setup instructions for Xbox Remote Play here.
*Please note: You will need to complete the initial setup on the same network as your console.
2) Ensure both your phone and Xbox app are up-to-date.
3) You will need an internet connection to the Xbox of at least 7Mbps, but 15Mbps or faster is optimal for the best remote play experience. This means the Xbox needs an upstream connection at least that fast; check that your ISP upload speed is adequate for the Xbox’s connection.
4) You will need 5Ghz Wi-Fi or Ethernet. While 2.4Ghz networks will work, it’s not optimized for game streaming, even if the speeds are adequate.
5) Reinstall the Remote Play app.
6) Please get in touch with the Xbox Support team here if you need further assistance with Remote Play.