im having an issue and hope maybe someone has seen it before. im running a ftb beyond server and there is problem with nether portals. it seems like half the people are sharing portals on the nether side. you go to the nether from your base and when u try to go back you end up in someone elses base. i have determined that some of the portals are being shared on the nether side and it happens to be only a few, as in 4 portals ive checked from diff bases take u to the exact same portal on the nether side. and 4 other players base portal take u to a diffrent particular portal. when i reset the nether it seems to switch it up a bit. also there is a weird issue where it seems to bounce you around when using the nether portal, sometimes for 15 seconds, sometimes it leaves u where u started. the mining world loads up quickly though and there are no issues with those portals
Please clarify what you mean by ‘bouncing around’, but you have essentially discovered a
bug of vanilla Minecraft. Nether portals are not magically linked; the blocks themselves hold no data. Instead, when you enter a portal, the game searches for the nearest applicable portal in the other world, and if it finds none, it creates it. If you have two portals close enough together (which is extremely close in the Nether and not close at all in the Overworld, as distance in the Nether is 1:8 with distance in the Overworld), then they will both lead to the same portal on the other side. And that portal will only lead to the closest analog in the Overworld, producing this behavior. Due to how distance calculations work with that 1:8 ratio, sometimes you can build a Nether portal, go through it to create one in the Nether, and have it create another new one when coming back to the Overworld!
Anyway, vanilla behavior. Most people have experienced this before. Nothing special or Sponge-specific.
right on. the bouncing around thing is when everyone on the server goes through their nether portal, either to the nether or back, they first get the loading screen for about 5 seconds, then they spawn for a blink of an eye somewhere, and then get the loading screen for about 5 seconds, then sometimes go to their intended destination, or they stay where they were to begin with or they land in someones base. teleporting doesnt have this behavior, it is smooth and fast when going between dimensions
I fixed this problem some time ago in 1.12.2. Which version are you using?