ssh: Login prompt never appears
You try to ssh/putty to a Maths computer, but nothing happens. No login or password prompt appears. If you are using a Linux/MacOSX machine you probably get the error message "no route to host".
This means that your computer has been switched off to save energy. Wake it up online, wait for a couple of minutes, and try to ssh in again. If you still can't connect, your computer may have been decommissioned. Try ssh.maths.cam.ac.uk which is always on.
If this fails too, there is most likely a networking problem such as a malfunctioning firewall. The Computer Officers will probably be aware of it already if it's on our end, and in any case emailing help@maths is unlikely to work until the problem is fixed. If you're curious you can use the "ping" and "traceroute" commands to locate the problem.