Cannot establish NTLM authentication channel

Dear All, 

I am re-initiating this discussion because it was unanswered in an existing post.

we are having problem regarding NTLM authentication. the error in the log states :

"Cannot establish NTLM authentication channel with <Domain Name>"

I have came across many of solutions mentioned here but they didn't work.

the log from Device using "tail -f nasm.log" in advance shell is as follows:

Apr 19 05:34:11.045684  [nasm]  net_ads_join() failed to join with server-><Domain name>             

/oss/net: /lib/liblber-2.4.so.2: no version information available (required by /oss/net)           

/oss/net: /lib/libldap_r-2.4.so.2: no version information available (required by /oss/net)         

dos charset 'CP850' unavailable - using ASCII                                                      

Failed to join domain: failed to lookup DC info for domain '<Domain name>' over rpc: Invalid workstati

on

SSO is working fine for users but we want to use NTLM also and for the record it was working before perfectly.

NTLM is configured perfectly according to this article

https://community.sophos.com/kb/en-us/123149 

issue was already escalated to Sophos Support but they seems to not understand why I need NTLM authentication.

please help me out with understanding the log and let me know what could be the issue with either Sophos XG or domain controllers.

thanks in advance,

Faheem Sarwar