The frontend (ecomplier.com), backend API (dev.ecomplier.com), and database (ecomplier_db) must ALL run on YOUR server. Right now your server has CORS locked to localhost:4200 only and returns "Invalid username or password" because it connects to the wrong database. You must: 1) Deploy the backend API on your server. 2) Connect to the correct ecomplier_db SQL Server database. 3) Add https://ecomplier.com and https://www.ecomplier.com to CORS allowed origins. 4) Ensure dev.ecomplier.com, @, and www all resolve to your server IP.