RE: Directory unreachable after installing Domino Hotfix 457 Ben Williams 17.Dec.14 11:56 AM Lotus Notes Sametime Standard 8.5.2Windows
Is your community server using LDAP and LDAP is running on your 9.0.1 server?
If you are not using LDAP then there is no interaction with your mail server so applying the hotfix shouldn't have any effect. I suppose if you are using native Domino authentication instead of LDAP and both servers are in the same Domino domain then the hotfix could have added something to the address book which has replicated to the Community server and is causing problems? Scrap that, 8.5.x HAD to use LDAP....
Can you use ldapsearch.exe to query LDAP? Use the bind account. Look for exceptions in the Trace directory on your Community server OS. Have you restarted the Community server after you took down the LDAP server? Sametime doesn't always like to reconnect to LDAP without some kind of interaction..