Remote office accessing our server

Hi,

I am noticing a strange problem in our network. If a user from a remote site tries to connect to a server in our network (which is behind the firewall), he is unable to connect or ping it (All rules and routing in the firewall are ok). If Igo to the server and ping the remote users IP address, then he is able to connect/ping our server. So each time I restart my server, I have to ping the remote user IP address for him to be able to connect our server.

Any solutions or suggestions please?