AlexRayner

This may sound like I am listing off the basics but have you tried checking the physical cable/cables for damage connecting the slow AP to the core switch? Things I would usually look usually consist of any cable damage at all and have the ends been terminated correctly? Also has the speed always been slower on this AP that you have listed? Could you roll the firmware on one of those AP's back (To avoid bulk rolling back and potentially causing another issue maybe) to see if it is a issue with the newest version of the firmware that has been pushed out? Hope this makes sense/Helps a bit!

I am going to throw a curveball out there but as someone who has used Spotify and Amazon (Not as much I must say!). I have quite enjoyed using Tidal. It creates about 7 daily mixes for you which all vary in genre of music most of the time and it is based off of what music you have listened to previously. It also has a 'My daily discovery' which is a playlist updated daily with 5 songs that you potentially would like based on your listening history. The only thing I miss from Spotify is the Wrapped feature at the end of the year - But Tidal does tally up how many times you listen to a artist each month and generates a 'My most listened artists' leaderboard each month. All in all I enjoy using Tidal over Spotify, Amazon etc and for £10.99 a month I find it is definitely worth it