Tim,
There are two types of connections that the relay installer attempts to make. If you use the automatic mode of the installers, it connects to my.nimsoft.com:80 to authenticate your credentials and retrieve the tunnel connection info. If you use manual mode, it does not do this because you provide the tunnel connection info yourself.
When the relay installer configures the hub, the hub should attempt to connect to your NoD instance on TCP 443. So in your case you should see attempts to connect to nms.mydomain.com:443 but not nms.mydomain.com:80. I do not think the relay installer ever tries to connect to your NoD instance on TCP 80.
If you are having problems with the connections to my.nimsoft.com:80, the latest relay installer supports proxy connections but does not work for all types of NoD instances. If you are having problems with the connections to nms.mydomain.com:443, you need to open direct access over TCP 443 through your firewall. The tunnel client in the hub cannot connect through a proxy.
If you need more in-depth assistance, it may be best to open a support case. Then we can address some questions in the specific context of your NoD instance.
-Keith