Cannot find the server on client servers list

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Using Docker 20.10.21
and Docker Compose v2.18.1

Hi ! I already had a server on another machine via LAN, and wanted to play another modpack; and found the mc router image to have both on the same machine.
I changed my docker compose file (https://pastebin.com/bQSW4UVS) to account for that, and moved it to home/mable/ instead of home/mable/mc-docker, where he was initially when there was only one server. I don't know if I should have moved it, but since the directory he was in before became the sole volume of the first server (I made "colony-docker" for the other one) I thought maybe it wouldn't be read correctly since I plan on not starting this container.

When I put "minecolonies.bubble.com" into the server address, I don't get a ping response.

I can see both servers loading via the logs, so I don't think it's that.
I think I messed up with the hosts part. Maybe it's because of the yml version (I changed the version from 3 to 3.8 without updating Docker/Docker Compose; I think it's just formatting ?), or that I wanna connect via LAN, and the hosts should have other ports or something.

Any idea on what I've done wrong ?

Start by reviewing the linked Docker Compose file and the mc-router container logs, then compare the LAN host and port configuration with the two backend servers. Reproduce the missing ping using the reported server address; done means both servers appear in the client server list and respond through mc-router.

Written by the indexing model from the issue text.