This is the new config UI for Synergy 2, which is much simpler (we removed the need to use IPs and server/client modes).
This is the legacy config UI for Synergy 1. It's only in the v2 branch because we haven't deleted it yet. The Synergy 1 UI is incompatible with the Synergy 2 UI, so that's why it's not working.
We have a Fedora RPM build for Synergy 2... how come you're not using it? By the way, Synergy 2 is party closed source, so you won't be able to build the new UI from source.