Sorry, the ratio is set to FIX_RATIO from the world loading routine, because the server is initialised before loading a map, at least for normal loading. Also if somebody joined a network game, and then wants to start the following game as a server, the core has to shut down and then reopened as a server. This closing logic when starting a server and a networkgame was running before was not correctly handled. And saving should cause a sync, if there are connectd clients. That I fixed as well.
If you aim at attaching a scenario to a running game, then karte_t::load is never called.
In r8476 the network starting and stopping logic is in a new function karte_t::server_switch I works also with scenarios which attach to a running gmae, at least I could connect locally. But the rule etc. are not displayed, when one joines.