You likely installed the print driver but missed the "Network TWAIN Driver." Go back to the Download Center, filter by "Driver Type: Scanner," and install that separately. Also, ensure your PC’s firewall allows port 2100 (TWAIN) or 5900 (WIA).
TA Triumph-Adler Download Centre is the primary hub for accessing essential software and documentation for all Triumph-Adler printers and multifunctional systems. You can access it directly via the official Triumph-Adler Download Centre Key Resources Available triumph adler download center