I’m sorry there is nothing wrong with Nextcloud running as Docker container behind Traefik. Below results from Windows 10 desktop client 3.3.6 against Nextcloud Docker container 22.2.3 running on old Core i3/16GB RAM where container lives on magnetic HDD with ZFS filesystem:
Download from NAS is definitely faster but NC is close enough on hardware limits… 570 Mbps is far more you need for daily usage…