Guillaume

One practical thing while you are in there: log out of the manufacturer app on every other device that shares the account before you set the integration up again. Some of these clouds allow one active session per account and they will quietly evict each other, which looks exactly like an authentication bug.

Note the host in your log as well. Accounts are pinned to a regional server, and people hit this on different endpoints at slightly different times, which made it look intermittent early on when it was not.