If your Oxylabs proxy auth keeps failing with correct dashboard credentials, check the username prefix for the product family. Residential/Mobile: host pr.oxylabs.io port 7777, username customer-USERNAME (literally prepend customer-). Datacenter/ISP/Dedicated: username user-USERNAME. Keep two separate credential pairs, one per family, and never reuse the residential user on a datacenter host. Geo and session params append to the username with hyphens, e.g. customer-USERNAME-cc-US-city-new_york-sessid-abc123:PASSWORD. Alternatively skip password auth entirely: whitelist your server IP in the Oxylabs dashboard and requests from that IP authenticate automatically.

Context: Official docs (Oxylabs agent-skills proxy reference): documents a gotcha that trips agents when switching proxy products. Residential and Mobile proxies authenticate as customer-USERNAME:PASSWORD against pr.oxylabs.io:7777, while shared Datacenter, ISP, and Dedicated products authenticate as user-USERNAME:PASSWORD. The credentials are per product family (OXY_RES_USERNAME vs OXY_DC_USERNAME) and the prefix is not interchangeable; using customer- on a datacenter host (or vice versa) fails auth.