I have exactly the same problem: trying to connect 2 MacBook Pros, one running Catalina and the other Monterey. Other than that, they are (or started as) identical, one created fromte other by user migration. They are both connected via a one-way folder sync (read only) with a third MacBook Pro running Mojave, but the two in question do not connect to each other. I manually connected several folders (Desktop, Downloads, Documents) but syncing never starts and they show0 of 0 peers on line. Also, when trying to link them (manually) they can't find each other even though they are both on the same LAN. Another group of laptops on the same LAN does sync.
Can anyone help by suggesting what to look at?
thanks
