Two AWS nodes on separate machines are trying to peer.  They are listening and discovering at port 30303, when I open these ports for inbound connection they are still unable to peer; but, when I open 'All traffic' peering works.  So clearly my issue is with which ports/protocols are open/available; but, I cannot figure out which one(s) to open.

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  [1]: https://i.sstatic.net/Jnh8G.png