[Bug] 502 bad gateway

[ISNing]

Describe the bug

502 Bad gateway when frontend try to post to http://{my_minecraft_server_hostname}:{port}/NekoMaid/?EIO=4&transport=polling&t=Oa_kULB&sid=2kgsZizX4E

To Reproduce

Simply put plugin and uniporter in plugins directory, modify the config of uniporter as is described in wiki and restart the server

Screenshots

Information

• Minecraft version: 1.12.2
• Plugin version: 0.3.3
• Uniporter version: 1.3.4
• Server core: (run /version)

This server is running Mohist version 1.12.2-320 (MC: 1.12.2) (Implementing API version 1.12.2-R0.1-SNAPSHOT, Forge version 14.23.5.2860)

Additional context

I've also tried to change the port to the one different from minecraft server, and it makes no difference

No error generated in server

>nekomaid diagnostic

[20:12:26 INFO]: [NekoMaid] Diagnosing URL: http://{...}/NekoMaid?EIO=4&transport=polling
[20:12:27 INFO]: [NekoMaid] Diagnostic Result: Successful connection.