The server is alive again, it runs on 1.6. You can play with a 1.6 client.
We use docker now because it was faster to make the server at leas playable again so this is also a temporary solution till asturel have more time to deal with the whole upgrade stuff.
Don't ask when this will happen, you can play, your progress won't be lost. When the full upgrade is started it'll take several hours.
Maybe in a few days/weeks/months.