GM! coinos.io loads fine for me just now (15:15 CET), so it may be something on your side of the line rather than a coinos outage. Worth trying: a different network (mobile data vs. wifi), another browser or a private window, or a different DNS. If it opens on one and not the other, it's your ISP or DNS, not your wallet.

are you using v3?

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?

the classic