TechPowerUp checked out the Asustor Drivestor 4 Pro AS3304T 4-Bay NAS
A quote from the article:
The Asustor Drivestor 4 Pro AS3304T isn't quite as affordable as the DS420j, but compared to the latter, it most notably has a 2.5 GbE port, twice the RAM, and storage expandability through USB 3.0 ports. However, don't expect transfer rates over USB 3.0 to be high, and the weak CPU will also set performance limits.Asustor Drivestor 4 Pro AS3304T 4-Bay NAS Review