I bought the Roku Express 4K+ and I'm actually having the same problem with Roku Express 4K+. YouTube constant buffering same as streaming stick 4K and TCK Roku. What is strange is that YT on my LG TV works fine. So it's not my network/WiFi etc. The Streaming Stick is attached to LG TV so same distance etc. Yeah, if anybody could help with this mystery I would appreciate it. All I can think of is the YT app on Roku somehow doesn't work but it does on LG(?).
TCL/Roku TV
Roku device model: TCL model 32S357, harware ID H104X
serial number: X020006P5TTC
device ID: S0LEJ32P5TTC
OS version: 13.1.4-build 1512-DD
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Roku Streaming stick 4K
Roku device model: 3820R2 - Roku Streaming stick 4K
serial number: X02522XT5T16
device ID: S0J732CT5T16
OS version: 13.1.4-build 1510-E6
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YouTube app
version/build: 2.23-build115025180
Tracker ID: Just goes to Home as soon as I press home button