Accoding to CS281915, it is not possible to use the preference "Preferred File Server" for ThingWorx Navigate users.
I would like to enhance this feature, as ThingWorx Navigate is basically useless for ThingWorx Navigate users in Asia, retrieving data from a Windchill master server in Europe.
Also, loading the OOTB Navigate Mashup page is approx. 8-9MB of download, which also takes unreasenable long time to load for remote ThingWorx Navigate users. I have bben informed that it is possible to have several ThingWorx Navigate instances connected to 1 Windchill instance. It just does not make sense to have a ThingWorx Navigate instance remotely, if the data has to be retrieved from the Windchill master instead og the Windchill RFS.
I hope you will implement this feature, and mybe slim down the mashup load size, in order to make it useable for remote ThingWorx Navigate users.