If this is a paid subscription channel, most (all?) of them have some limitation on the number of simultaneous streams you can have going at once. A limit of 1 stream is uncommon, but not unknown. What channel is it?
Roku Community Streaming Expert
I am not a Roku employee, only a user like you. Please, no support questions via private message -- post them publicly to the Community where others may benefit as well.
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Ultra 4800 | Streaming Stick 4K+ 3821 | TCL Roku TV 43S245/C107X