I believe you're missing the playlist parameter, which needs to be set to the video id, as shown in @C3roe's answer.

Note the added &playlist=1u17pS4_tw0, I've just tested it and it should work! :)

<iframe width="560" height="315" src="https://www.youtube.com/embed/1u17pS4_tw0?si=V06Ss5eD89_PBShj&controls=1&autoplay=0&rel=0&modestbranding=1&mute=1&loop=1&playlist=1u17pS4_tw0" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>