Actually I have a 2TB mbl too.
But i can copy with 48MB/sec til 50. so very fast for me.
The only thing i did was putting a30.-€ gigabit switch between my Internetrouter and PC
so all other Devices are connected via Gigabit.
I also have Antivirus Running and Firewalls
I copied about 1,2 TB to MBl and yes took about Ithink 6Hours or so