If you are behind a firewall, it can be still available to synchronize your local PC clock with time servers. You just need to know what type of proxy you use, its address and port number. Currently Advanced Time Synchronizer supports HTTP, SOCKS4, SOCKS4A and SOCKS5 proxy servers. Unfortunately, most proxy servers do not support UDP datagrams, so the time servers configured to SNTP protocol and TIME and DAYTIME protocols with UDP network protocol will be unavailable, if you using a HTTP, SOCKS4 or SOCKS4A proxy server.
If your proxy server requires authentication, you must check Use authentication for the server check box and specify your user name and password in the corresponding boxes.