Difficulty connecting to our game server on macOS

Hi,

I run into a connection error (please see attached) every time I try to log into our server using my Mac. To give a bit of context, our game requires the user to type in their username (email address) and password right at the beginning of the game (the log-in screen appears right after the initial logo screen). The game was initially developed on a Windows PC. But, we recently tried to transfer the project over to Mac. On Windows, we can easily log in and connect with our game server. But, on Mac, Unity throws the attached error every time we try to log into the game.

I can't identify what's causing the issue on Mac. I'd be grateful for your advice on how to fix the issue.

P.S. Sorry, this is my first time posting on Unity Forum, so if there is any problem with the format of my post, please let me know. Thanks very much.