Whenever a nether portal is created on realms, and I have had this problem on every realms server I have been on, all portals created after the first portal in the overworld connect up connecting the the first portal in the overworld, so no matter where you are in the nether when you create the portal or how far away you are from the portal in the overworld when you make a new one, they all lead back to the same point. This makes exploring via the nether and nether highways impossible to do.