Confirming that the TRENDnet TUC-ET2G USB-C to RJ-45 Ethernet Adapter is working while plugged-in to the back of my Synology DS1520+. Repeated 2GB file copies result in ~270 MB/sec transfer speeds.

The TUC-ET2G adapter comes with a USB-C to USB-A adapter that must be connected in the correct orientation. Even though there's a very small notch on the connector, it's easy to miss, and if you connect it backwards, you'll only be able to achieve a 1G connection.

Description of your products

Synology DS1520+
DSM 7.2.1-69057
3 Seagate IronWolf Pro 16TB drives
SSD read cache only (no write cache)

Description of your environment

Installed driver: r8152-geminilake-2.18.1-1_7.2.spk
Connected from PC to TRENDnet TEG-S380 8-Port Unmanaged 2.5G Switch
Cat 5e cables
Enable Jumbo Frame, the MTU value is 9000
Reported 2500 Mbps, Full duplex connection