Tails has got it right, but I'm not sure if he answered your question
I think it's similar to my troubles (see this thread). A powered dropper can power components next to it. In the end, we get something that programmers call "race conditions": Several things happen in theory at the same time. But they happen after each other, because processing in minecraft is not parallel so there has to be some order.
I'm still learning, but I think this example covers it: Assume you strongly power a hopper A that has redstone components B and C left and right. (So the layout is BAC.) When A is powered, both B and C are in theory powered at the same time. But in reality, one of them is powered first. The order may depend on the location or whatever Minecraft uses to organize structures (chunk boundaries, last time updated, no idea).
https://minecraft.gamepedia.com/Tutorials/Quasi-connectivity gives some insight into QC.
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Did you portforward properly?
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1. Post results from speedtest.net of your and your friends internet speed.
2. Leave the server IP setting in server.properties blank.
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Did you portforward properly? Which IP address are you giving your friends?
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Get rid of wizardanimalsbeta. It's client side only.
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Post a screenshot with F3 enabled and your JVM arguments.
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Report these kind of posts via the report button so the mods can take care of them.
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Second link is broken, use paste.ubuntu.com, cause pastebin sucks.
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BedBenefits is crashing.
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Add PAUSE at the end of your startup script.
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They're on mac...