Clients can't connect to the Dedicated server

Hi

We have a dedicated server running on our LAN. Using the the computer that built the server to build PC or android clients works well, and the clients can connect to the server with no problem.

Our problems:

  • when we build the client on a different computer, the clients don’t connect to the server.

  • the mobile preview does not connect to the server (Getting this work would be very convenient and save tons of time)

I am wondering if the server has some security protection that rejects this kind of connection request.

Thanks in advance.