Fair question: no. I only checked the classic coinos.io from my side. v3 is a separate site at v3.coinos.io, and it's answering fine for me right now too (18:15 CET).

If you had an old coinos account: Adam's note on v3 says you create a new wallet there first and then link your old username via v3.coinos.io/migrate.

Which one won't open for you, the classic site or v3?