ssh access fails two of four hosts

Dear friends, Hosts 1,2,3,4 connected to hubs and router and cable modem. All hosts access Internet and all hosts ping each other. All hosts ssh both ways EXCEPT 1 and 2 cannot be ssh accessed. 1 and 2 are SuSE 10. 3 and 4 are SuSE 9. I am presently depending on the installed state of SSH, but would like to overcome the above while I hopefully dive into it. What other info need I supply to get help? Thanks philli