What prevents port 1352 from receiving calls?

Hi. Last week one of our Domino servers stop receiving calls from other Domino servers in the same domain, as well as Notes clients. We discover that port 1352 was not working properly, while port 80 worked pretty well all the time. Just for testing, we changed the "broken" port to 1353 and it worked. So far, we do not know what prevents port 1352 from receiving calls. Have you ever heard something like this?
Gee, that's a good one. I don't have an exact answer, but I think it is a configuration issue, rather than anything actually broken. Keep in mind that IP ports are not really hardware ports at all, but software addresses within a communication protocol. So there is nothing to "break" (as far as I know) at one port versus another.

You might try switching the port back to 1352 and see if it works now. Maybe it was not really the problem, but something else was going wrong with replication.

You might also try looking at Domino R5 Admin Help / Index / Port. There are lots of entries there about setting up port addresses, so you might find something there that applies to your setup.