Client disconnects can be tricky to troubleshoot, but one important setting to check is to assure 4D's client-server connections timeout is set to a value lower than the router's timeout. The reason for this is to allow 4D to properly close any idle remote clients gracefully instead of the network forcefully killing it, similar to properly closing a program instead of force quitting.

The client-server connections timeout setting can be found under Design > Settings > Client-server and is set to 1 minute by default. The router setting will be different per router, so it is best to check online for the router's documentation.