Slow download speed on WiFi

[Brintamatic]

Hello, my wife and I both have iPhone X on the latest iOS 11.3. We just started using Spotify (came from Apple Music) per recommendations of some trusted YouTube creators. However, we are having really slow download speeds on WiFi. On LTE, it works fast but I would rather not eat away at my data limits. Also, I should mention that I have gigabit fiber service and get 300-400Mbps speedtests on my phone. To make sure it wasn’t our router, we’ve tried to download on three other WiFi connections (friend’s homes). In researching this from previous Users with this same issue, I’ve found that people have had three main solutions:

1. Setting the HTTP Proxy to Automatic on the phone WiFi settings. I tried this and it worked one time but the next time I tried (on the same day even) it is back to slow download speeds.

2. “It just magically started working one day”???

3. Setting back the WiFi connection to a slower connection like a B connection. My iPhone has been connected through either AC or N depending on where I am. 

Any help would be appreciated.