Here is one reason why you should cleanup SAN’s in your certificates. Experienced one scenario where a customer moved from one hosting provider to another and was unable to federate after the move. Continue reading Keep Your Lync Public certificates up to date.
You have installed Lync edge server and have issues federating with some or all of your partners. If you check the eventlog you might see multiple errors like event Source : “LS Protocol Stack” and Event ID 14428.