48hours * 60minutes * 53megabytes/min == 152640 megabytes (48gb + 104gb)
53megabytes/min / 60seconds == 0.883333333333megabytes/sec, or 904.5333kilobytes/sec
904kilobytes/sec == 7236kilobits/sec (or kbps), or a bit over 7megabits/sec (or mbps)
I just did a quick test on my ROCK install at home:
Over WiFi, from a Macbook Pro running Mac OS 10.12.6, to a slow ExFAT formatted USB2.0 5200rpm Western Digital Passport drive from 4 years ago, connected to ROCK running on a NUC6i5, I am getting 47megabits/sec. I’m also upstairs and bouncing through 2 Eero mesh WiFi routers before going ethernet to the NUC.
Something is wrong on your SMB sender, your network, or your drive is failing.