Hey, as I own server, with Origins mod, there are some players. One of my players told me, he doesnt have his reach. I tried it, and discovered that Enderian doesn't have the reach when not OP. Is there a way to fix it?

I couldn't reproduce this issue. Do you maybe have some other mods on your server (some form of anti-cheat mod maybe?) which could prevent their reach from being increased?
Either way, for extending the reach, Origins relies on a third-party library mod called Reach Entity Attributes. If you still have this problem, please post an issue on their issue tracker. Feel free to link back to this issue if you do so.