Nether portal linking broken on server software.

Basically, I decided to make a villager breeder in my private SMP (which runs in the official bedrock server software). Later that same day, another player contacted me (I'm the server admin) complaining his nether portal was slinking with mine. Initially I was confused, and thought it was because he was close to my portal. no. to my surprise, he was over 100 blocks away. and still kept linking with my portal. I honestly don't know why that happens.

NOTE: My portal is not a normal 2x3, bit a 5x3 (or 6x3 not sure) portal in case that matters.