Somebody was asking for help with Nether portals but now I'm getting an error message trying to answer.
Maybe the problem was solved and the thread deleted but here is my answer in case it's still needed.
If not it might still be useful for somebody else.
--
If you check the coordinates of your new portal in the Overworld, divide the X and Z numbers by 8 and build a new portal in the Nether at those recalculated coordinates that portal should take you to the one in your base.
--
The new portal in the Nether doesn't have to be at the exact coordinates but the X and Z coordinates can't be off by more than 16 blocks (each) or using it will make a new portal in the Overworld.
The Y coordinate (height) can be anything from 1 to 127 as long as there isn't another portal whose coordinates would be closer after recalculation of X and Z (divide by 8 going to the Nether and multiply by 8 going to the Overworld).
(Portals above the upper bedrock in the Nether work going to the Overworld but you can never port to them.)
Somebody was asking for help with Nether portals but now I'm getting an error message trying to answer.
Maybe the problem was solved and the thread deleted but here is my answer in case it's still needed.
If not it might still be useful for somebody else.
--
If you check the coordinates of your new portal in the Overworld, divide the X and Z numbers by 8 and build a new portal in the Nether at those recalculated coordinates that portal should take you to the one in your base.
--
The new portal in the Nether doesn't have to be at the exact coordinates but the X and Z coordinates can't be off by more than 16 blocks (each) or using it will make a new portal in the Overworld.
The Y coordinate (height) can be anything from 1 to 127 as long as there isn't another portal whose coordinates would be closer after recalculation of X and Z (divide by 8 going to the Nether and multiply by 8 going to the Overworld).
(Portals above the upper bedrock in the Nether work going to the Overworld but you can never port to them.)
Just testing.