Uneven color noise on prints from Epson ET-8550

The prints on my ET-8550 have noise regardless of the printing quality i choose. I tried various quality settings, but the basic issue remains and seems to be related to uneven transport. I've made two example prints in 15x10cm format. The prints were started on the printer itself from USB storage. Then scanned at 600 dpi where the noise is readily apparent. Please have a look at the scan here: https://wolkig.ch/index.php/s/bLokMS9TfJym5m6 The bottom print was made using standard quality, the upper print was made with ultra glossy setting. Both prints are on Epson Glossy Photo Paper. I chose t

Question by sba on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.