RTBlintAlpha
nbr 6: Unsupported Device
What it means
The bidder does not buy on this device or OS.
A bidder returns nbr on an otherwise empty BidResponse to say why it is not bidding, instead of (or alongside) an HTTP 204. Code 6 is unsupported device.
What to do about it
The request was fine; the bidder chose not to buy. Unsupported devices, blocked publishers, unmatched users, and frequency caps are demand-side policy. The only sender-side lever is signal quality: complete device and app/site objects and usable identity signals reduce unmatched-user passes.