I have an M1 MacBook Pro 16, running BTT 4.334. If I put my Mac to sleep by closing the lid, then BTT Remote (running on my iPhone) fails to connect when I reopen the lid. It's as though the TCP/UDP port has been closed and BTT doesn't reopen it.
I just verified that this is the case using "lsof". Before sleeping I can see two open TCP ports and two open UDP ports. After waking, both ports are gone.