Hi,
You are correct. EMS is having a problem handling "Digest or Basic" authentication. It turned out that the presence of the stale attribute in a digest authentication header somehow violates an internal state, causing the authentication failure.
If you cannot change the device’s authentication type to either "Basic" or "Digest", we can do a special build particular to your device. However, our tests may be limited.
Let us know your take on this.
Xai