Apologies, I misread your last comment peashooter. It sounds more similar to the latter, but I don’t know enough to say for sure as I haven’t checked the cooldown the way they have. I’ve just assumed a ~30 second cool-down as I thought was standard.
edit: also, the portal is long established. I’ve been through it both ways several times.
The file was too large so I have uploaded it to dropbox here:
As for what the issue is, it's detailed above?
Mobs will not enter a second portal within the nether. I take them through one at point A in the overworld just fine. I take them to the second portal within the nether that leads to my base at Point B. They will not enter the portal that leads to point B in the overworld.
I can however take them back through the portal they came through back to point A within the nether.
So, I'm not sure why they're unable to travel through point B's portal. Cooldown has passed, breeding them and trying to send their offspring through also doesn't work.
The portal randomly creates a new overworld portal a decent ways from my base for some reason despite the overworld portal at point B being the original portal I made and I never destroyed/relinked the one it created in the nether to link up to a different one. It's just randomly deciding to drop me somewhere else in the overworld.
So the issue is twofold - mobs refusing to go through point B's portal, and the portal for point B deciding to make a second portal in the overworld for some unknown reason despite the original portal at point B being the one that created the portal I use in the nether.
Does that make sense? :/
I have also tried this UNMODDED as I mentioned above - vanilla, no fabric. All mods turned off. Same issue.
If I try pushing them through the portal they came through to get into the nether, they go through without an issue. For some reason they won't go through my base portal in the nether though.
I've also tried boats and rail carts. They don't work either.
I should add - my nether hub is not on the nether roof. It's just within the nether.
Bump