How to speed up bulk load

I have two NAS drives, an EX4100 16TB configured as factory default and an EX2Ultra 8 TB which I reconfigured to RAID 0 to give me 8TB and presumably better speed.

I want to bulk copy 4TB of data back to the EX2Ultra after reformatting it. I’ve been at it for almost three days now, and am not even a quarter of the way through it.

I read the article on speed issues, (https://support-en.wd.com/app/answers/detail/a_id/15542/kw/fast%20transfer) and I’m a little confused. The table suggests that Fast Ethernet is slower than Wireless 5 GHz, which I’m using. I would have thought it would be faster on the wire?

There are two ethernet connections on the EX4100 and only one on the EX2Ultra. I have them each connected to my ISP provided router/Wifi.

Would it be better to connect it from the router to the EX4100 and then from the EX4100 to the EX2Ultra?

Also each of the drives have 2 USB ports, but when I try to connect my MacBook Pro to the USB port, I don’t see the drives display in Finder. Is there a way I can wire the computer directly to the drives to improve performance either through the USB or the ethernet?

Any advice will be appreciated.