Then transfer the two sets of files you separated earlier, one to the first IP address, the other to the other. I have used a Mac one time in my life, about 20 years ago, so I have no idea how you do that, but I am still sure that it is somehow possible (in the worst case, by not mounting the NAS file system directly on the iMac, but by using something like a scp/ftp/rsync file transfer instead. Then, connect from the iMac to the NAS twice at the same time, once for each of the two IP addresses of the NAS. Then split your 100GB of files into two sets, their size roughly corresponding to the relative speed of the two connections. Put both your devices on Ethernet and Wifi and make sure Ethernet/Wifi are in different subnets. While it is complicated (or, with cheaper devices, impossible) to do this on the link, network, or routing layers, you can use both Ethernet and Wifi by 'bundling' your two links on the application layer easily.
If not, is there a way to enable transfers to use both?
