Needs wifi hotspot from phone to be reliable - why?

[awojtas]

I'm using a 2GB RAM / cheapo Android head unit from aliexpress, which only supports 2.4Ghz no 5Ghz wifi.
It's connecting using native mode using HUR 3.1.0.

However in addition to the native AA bt/wifi connection for the phone with the head unit, I always need to have a wifi hotspot running from my Android phone, otherwise music barely works and HUR progressively freezes. HUR connects without this wifi hotspot, but it's laggy, jerky, and the music stutters like crazy.

With the wifi hotspot, it's nearly seamless - maybe one audio skip every 20-30mins - and Google Maps runs are a higher fps than I've seen the head unit ever do before using HUR.

I don't totally mind the hotspot but it is a little annoying to have to always start this on my phone.
My phone is an oppo find x9 pro. All the wifi assistant settings are turned off on the phone (auto connect to best wifi, dual wifi acceleration).

The hotspot is 2.4Ghz since the head unit doesn't support 5Ghz. The hotspot settings are WPA2/WPA3 personal, "use wifi 6" enabled.

Aside, HUR is rock solid except when scrolling on Spotify, guaranteed to freeze. I alt-tab on the head unit, swipe to close HUR, reopen it, and it's fine again - until I forget and swipe through a playlist in Spotify. The music stays playing in the background while this happens.