[2020] "Server Error: A third-party provider returned an error to the backend service. : 1127"

This should no longer be an issue. If anybody else is still experiencing this, restart the Steam client and consider performing a DNS Flush.

Try re-launching Vermintide 2 please @tigtot. I believe this error is occasionally shown to new players.

Could you send me the URL to your Steam profile please @tigtot?