Slow connection once the PC is network connected

Hello, I am deploying a database to customer PC, which will be only connected by local application.

However, I realize once the PC is network connected, the connection take extremely long time (around 10 seconds)

May I know why this happen? I was wondering whether is there any workaround to overcome this?

I connect the database using C++ code

PQconnectdb("dbname = ProductionFactory user = postgres password = password");

Thanks.

Thanks and Regards
Yan Cheng CHEOK