I will try my best to describe the situation, while we've been trying to figure this out:
We have this SQL Login [LA] which shows successful connection on principal server in the sql error logs [connection made from various apps]. This login shows successful connection on its mirror server as well.
Now, here is this another login [LB] which connects successfully on principal server but fails to connect on mirror server. [same application as above login LA connects]
run sp_help_revlogin on both servers and matched the hashed password for login [LB]. Thus that confirms password is same for this login in terms of SQL login for both principal and mirror.
SID's of login is same at both servers, so this should not be a problem as well.
Application uses same creds to connect on principal which is a success but shows login failed on mirror server.
Since something is making the login unsuccessful attempts, login keeps getting locked out.
What else can i check as a DBA before passing this as an application issue to the app owners?
Please help me troubleshot to find the root cause of this issue, thank you.