Hi Ihaeger,

I am working with Rakesh in this.
Yes AD is listening on port 636.
Ran the below command from LDAP Proxy box and returning success.

nc -v -z ******* 636
Ncat: Version 7.50 ( https://nmap.org/ncat )
Ncat: Connected to ******:636.
Ncat: 0 bytes sent, 0 bytes received in 0.03 seconds.

Also tested via Apache Browser and connecting to port 636.