I have Spotify Premium and a new iPhone XS Max 512GB (420GB free) running iOS 12, and over the course of the past four days it downloaded only 50 songs (out of 2200 songs).

It seems to only download (extremely slowly) when the phone screen is on and open to the Spotify app (i.e. on top), while connected to my home 5ghz or 2.4 ghz networks (tried both). 

My home network/internet speeds are 'as normal' wich show 103mb/s down and 10mb/s up (slowish, but that's with two others streaming video at the same time, and I'm in a small rural area). Regardless, it should have downloaded more than 50 songs in 4 days... It wasn't slow like this on my old iphone 6s...

Anyone know what the problem is?