NAT does not work if input and output port are different
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Hi there
I setup a Minecraft server on the standard port 25565 using NAT, that works fine.
After seeing some intruders I changed the input port to 20000.
But the friends, which could connect on port 25565 before, could not join Minecraft anymore.
All I changed was the input port number!
Does NAT work only when the ports are the same?
What can I do, to fix the problem?
Thank's for any help!
Mutzli
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Hi @Mutzli
Thanks for posting in our business forum.
It does not have to be the same on external and internal. Internal port can be the desired 25565. For the external, you can do a different one but your friends has to change the port to the new one you've changed. Or they cannot join.
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also, potentially stupid point but...
When using non-standard ports, launch the client, go to multiplayer, go to "Add Server", put the name in, but when you put the address, put "<ip address>:<port>"
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Yes, I restarted/rebooted it several times.
Now I have both NAT in parallel, one with both ports on 25565 and the other on 20000/25565.
The one with 25565/25565 is in use and also works fine.
The other with 20000/25565 is frequently tested, but all attemps to connect failed so far.
Mutzli
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Hi @Mutzli
Thanks for posting in our business forum.
It does not have to be the same on external and internal. Internal port can be the desired 25565. For the external, you can do a different one but your friends has to change the port to the new one you've changed. Or they cannot join.
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We have tried on 20000 first, didn't work.
Back on 25565 it worked again (of course with reboot first...).
Mutzli
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also, potentially stupid point but...
When using non-standard ports, launch the client, go to multiplayer, go to "Add Server", put the name in, but when you put the address, put "<ip address>:<port>"
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Hey Mutzli,
Your friends might need to update their connection settings to use the new port (20000). NAT should still work, but they'll need to adjust Lotus365 and their settings to match. Hope that helps.
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Im on holidy now, please wait about 2 weeks.
But I'm pretty shure all is setup correct. Other NAT (1:1) are perfectly working.
Mutzli
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