could cause a heart attack or a stroke. But, this is similar. https://www.amazon.com/Snoring-Advanced-WoodyKnows-Breathing-Sleeping/dp/B07KWRLP4L I use this to keep my mouth shut while wearing my cpap mask. It makes me breath through my nose. He could have clogged sinuses, a deviated septum, or what ever. Do not tape his mouth shut. Perhaps a short term solution is ear plugs. But to be clear, do not put earplugs in his mouth. Good luck.
This does not have glue in the middle:
https://www.amazon.com/Snoring-Advanced-WoodyKnows-Breathing-Sleeping/dp/B07KWRLP4L
But It’s not my favorite, feels oversized for my face.