I noticed my conduits aren't reaching the right range on my Realm, so I tested the conduit range on a creative superflat world, the maximum range is supposed to be 96 blocks with a full frame, but the conduit is only reaching 80 blocks in two of the four directions and 64 blocks in the other two directions. The test conduit is built at 0,0 and the last blocks along the x and z axis that will give conduit power are 79,0 -64,0 0,79 and 0,-64. I don't know if this is an intended change, but everywhere I've looked for information on the range it has listed the maximum range as 96 in all four directions. The difference in range different directions makes it seem more like a bug.
In the picture the red dots are the last blocks that will give conduit power, the other dots are 16 block increments extending out on the axis starting at 32 blocks away from the conduit and ending at 80 blocks away.
The conduit range is limited by the Simulation Distance, which for realms is always 4 chunks. So, depending on where in the chunk the conduit is placed, the maximum distance will be between 64 and 80 blocks.
You can have another player (or afk account) at the conduit to keep it in the simulation area for a multiplayer world.