"Today everything is failing."
Translation:I dag mislykkes alt.
You version is also correct.
The only difference might be someone's interpretation of where the emphasis lies. E.g. you start the sentence with Everything, so the emphasis is on the fact that it's not just some things that have gone wrong today, but literally all things. The DL sentence places a bit more emphasis on the time, so it might be interpreted more like 'yeah, everything's gone wrong today, but it wasn't like this yesterday/it won't be like this every day'.