Nether portals will link up even if they are a thousand blocks away. All nether portals will start to link up with the first one created, the only way to stop the glitch is by breaking the nether portal inside the nether, but new portals will still link up with another portal, or by making all new nether portals inside the nether. I started at 2600 X but the portal linked up with one at 3600 X. This also affects Nintendo switch edition