Has there been a change to nether portals spawn properties?? I make a portal in over world, go to nether, then return and a new over world portal opens a couple of hundred blocks away. Also 2 portals in over world 1200 blocks apart lead to same portal in nether. What am i doing wrong?
Can you post the exact coordinates for the portals?
Both the left and right sides of the portal in the Nether that went to the "wrong" portal in the Overworld.
All of that could be perfectly normal and the way it's always been.
You understand about how you divide the X and Z coordinates by 8 when traveling to the Nether and multiply by 8 when traveling to the Overworld?
When you enter a portal, whether it's been used before or is brand new, Minecraft converts the coordinates and looks for a lit portal in the other world within 128 blocks in the X and Z directions and Y from 1 to 256 in the Overworld or 1 to 128 in the Nether, if it finds one or more it sends you to the closest otherwise it makes a new one as close as possible to the converted coordinates, within 16 blocks X and Z I believe.
Because of the coordinate conversion a portal in the Nether has to be within 16 blocks of the converted coordinates of an Overworld portal in order to connect but an Overworld portal can be 1024 blocks away and still connect (or maybe 1023).
Likewise, if you do your calculations correctly you can have 2 Overworld portals almost 2048 blocks apart going to the same Nether portal.
The way to fix it is to write down the coordinates of a portal, do the conversion and then build a portal as close as possible to the converted coordinates in the other world.
The Y coordinates only matter when calculating which portal is the closest (plus you can't use a portal to travel above the upper Nether bedrock).
If your first Nether portal got placed 16 blocks from where it belonged than the other half of it could be 17 blocks away and therefore not connect.
I'd bet that if you test going through both sides then one side will take you to the original Overworld portal and the other to the new one. (That's left vs right when viewing the portal frame as an O, not front vs back.)
Thanks for the reply, I never thought of it being on a chunk border. I have got them far enough apart now by messing about before I read this but I'll check the chunk thing and mess about more to see what happens.
It doesn't / shouldn't matter if it is on a chunk border - "16 blocks", while indeed being the width of a chunk, refers to the maximum distance the game can see a portal in the Overworld from the Nether; the search radius of 128 blocks (257x257 around a single portal block) is determined after applying the 8:1 conversion between the Overworld and Nether; for the same reason portals in the Overworld can be up to 1024 blocks away from a portal in the Nether (even further when accounting for the width - even a normal (2 block wide) portal can actually take you to two different portals in the other dimension, which becomes more likely when larger portals are used, so you want to make sure the coordinates in each dimension are as close as possible to the ideal ones, which is likely to not be the case if the Nether-side portal appeared inside of a cave or on a narrow ledge, as opposed to a large flat open area):