So runuo is set to this port and with login -using razor your adding this port? Have you connected to your server in the past? If not would your serverlist. be set correct? Your not giving much information so all I can do is ask questions

With using 2599 and not port 2593
line16: private static IPEndPoint[] m_ListenerEndPoints = new IPEndPoint[] {
line17: new IPEndPoint( IPAddress.Any, 2593 ), // Default: Listen on port 2593 on all IP addresses
You changed this here: RunUO-2.0-Final\Scripts\Misc\SocketOptions.cs
changed the 2593?