After setting up the new MOBO and CPU, download the slow version.
Currently, the speed is 1.7 mbps; recently it reached 100 kbps.
How 'new' is that mobo? Possibly it can't handle speeds above 1mbit/s. (That equals 100-150kb/s)
ASROCK b450m pRO4 model
The board handles 1 gigabit per second.