I'm probably misinterpreting your post: When you are talking about the config switch; are you talking about setting the channel, mode or the config itself? The 1,2 and 3 settings for config control whether the unit is in 'use', 'cross-over config' or 'router config' mode.

If the RFX is properly configured you need to have config set to 1 for 'use'

It sounds like you may have some left-overs sitting in the RFX9400 config. You've indicated that it works in network mode: Have you queried the RFX9400's internal config via cross-over cable or router in your browser to ensure that all of its network settings have been removed and that the units' internal config is really in standalone mode? By nature of your description it sounds like the unit was configured to work in network mode and those settings still remain.