Pick a maintained player
Use the developer’s official download or a verified store listing. Confirm that the app accepts your service’s sign-in method. A web player, if supplied for your account, may support different features from a desktop app; do not assume an arbitrary website is a valid login destination.
Add and protect your profile
Use the exact server or playlist information issued for your service. Playlist links can include passwords, so keep them out of public forums, screenshots and shared browser history. Remove saved credentials before handing a computer to another person.
Diagnose one change at a time
Try a known working live stream and an on-demand title. If the desktop works but the TV does not, compare player compatibility and the local network connection. Close unused streams so the test stays within your connection limit. Send the app version and error wording to support if needed.