Everything runs smoothly on Windows and MAC! Is the latest firmware installed? UGreen releases new firmware every month or so, as do the client and Apps-SW. The DXP8800 Plus has two network connections, are they both configured correctly? Be careful with jumbo frames!
I have connected several Macs via the network myself. No problems so far. Have had the dxp8800Plus for a few months. Why don't you try the AutoMounter app on your Mac? It solves many connection problems with the network.