Setting the trace has helped I believe

I see this which only appears when the encryptPassword is set on

 -> DBI->connect(dbi:Sybase:server=MY_REPSERVER;encryptPassword=1, rep
+serv_user, ****)
    !! ERROR: 2056 CLEARED by call to connect method
    -> connect for DBD::Sybase::dr (DBI::dr=HASH(0x1a723a8)~0x1a72420 
+'server=MY_REPSERVER;encryptPassword=1' 'repserv_user' **** HASH(0x1d
+1d640))
    syb_db_login() -> using global CS_LOCALE data
    servermsg_cb -> number=14021 severity=12 state=0 line=0 server=MY_
+REPSERVER text=Invalid login attempted by user 'repserv_user'
    clientmsg_cb -> ct_connect(): protocol specific layer: external er
+ror: The attempt to connect to the server failed.
[download]

That 2056 error (which is a Sybase syntax error) does not appear when encryptPassword is not set.

So it looks like a possible bug in DBD::Sybase ?

I'm not sure if that module is maintained anymore