Thanks to KOTH Kougar/Megafortress, I can now see the Server. Counter-intuitively, whereas using DMZ has always permitted access in the past, I have now as suggested forwarded some more ports in addition to ones which came stock with the router ( such as MSN Gaming Zone etc.) and the ones from many Cleaven/Sandman posts.
I got it to work, well I least I can see the test server.
I had already added the special apps for SFC based on the posts in the forum, but had had no luck - but running in DMZ seemed to always work.
I disabled DMZ off and I added in "Special Apps"
2300-2400 Trigger to 2300-2400 Incoming
27100-28900 Trigger to 28100 Incoming, and
28100 Trigger to 28100 Incoming.
One of those must have done it.
Still it was so weird that only SGO and Strayys were not getting through.