I couldnt join my server as it was thinking it was mismatched despite both having 1.5.4, until I went into 1.5.4 and changed hordes info .json, as it stills says 1.5.3

The meta info json wasn't updated properly for version 1.5.4 and as such the mod version 1.5.4 will conflict with itself when trying to connect 1.5.4 you can open the jar like a zip, open the default configs folder, open the json in something like notepad++, and update the version number to 1.5.4 to resolve the issue.