I have a similar situation. I am not sure if I should be posting in someone else’s thread but I havent found answers to my situation. Please let me know if its not allowed.
This is my thread: OSMC crashes on playing audio over network
OP, are you able to play audio files on osmc from the router.
My configuration is:
Raspberry Pi 2 running OSMC (ethernet to router)
USB drive connected to router (WD N750)/testing with USB flash drive before setting up a complete external HDD media hub.
I am able to access the video files on the same drive in the router, as soon as I play audio files OSMC crashes and restarts.
Everything(audio and video files) is accessible via other devices in my network.
For your situation, you might want to download the files in your computer first and then copy them to your HDD connected to your router. I tried to download files directly to the USB connected to router and it kept on disconnecting and many times I ended up with half of the files. I was trying the transmission client on mac though, not running directly from OSMC.