Ever played on a multiplayer server, built near other players and when returning from the Nether, surprisingly found yourself in another player's base? It's because of the 8:1 block ratio between the Nether and the Overworld. It's really weird though that you enter a portal in the overworld, and then when going back through where you came, come out of a different portal in the overworld. This mod fixes that issue.
NetherPortalFix keeps track of which Nether portals each player used when travelling between the Overworld and the Nether. When that player goes back through the same portal area, the mod returns them to the portal they came from instead of letting vanilla pick a nearby portal that may belong to someone else.
The 1:8 ratio remains, portals just get smarter and remember where each player came from.
NetherPortalFix must be installed on the server.
Forge
Fabric