Clients attempt to register to the server, when they try to connect the server does not allow it because the server can not contact the SMP.
Unable to connect to tickle server: System.Net.Sockets.SocketException: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond 10.5.128.29:50123
This issue was caused because of a firewall blocking communication from the site server to the SMP over port 50123.
*Note: This also applies to port 50124
To fix this issue open the firewall to allow all site servers to connect to port 50123 and 50124 on the SMP.
7.5 and later