status.quavern.net is the place to look. It is faster than asking us, and it distinguishes the two cases that feel identical from the outside: a service that is down, and a request of yours that was refused.
What the status page covers
Each service is probed independently — the API, the chat, myQuavern, the Quavsit API and web app, the Quavblok game server and its page, the download and update hosts. Declared maintenance appears there too, with the window.
When a service is in maintenance
The application says so rather than failing silently. Marl Code, for example, shows the message the team published for that maintenance when it meets a refusal during one.
When the status page is green and it still fails
Then it is your request, your plan or your account, not the service. The error carries a support code that names the exact condition; read what it says before retrying. Common causes with nothing to do with an outage:
a monthly unit budget or a spend cap reached on Quavsit;
a usage window exhausted on Marl;
an unverified e-mail address;
a key that was revoked, or that belongs to a different service.
Quavern help reference: service-status/en