Troubleshooting audio system

[Testaz]

Having an issue in my 2017 base wrx, factory audio system. One day driving most of my audio cut out. Seems as though everything but the driver door speaker and driver tweeter cut out. Checked fuses and everything checked out. Wanted to come here before I start taking my door panels off. Thinking maybe it’s the head unit? However it’s still functional and I have some audio, not all. Any advice before I dive in? Odd to think some speakers work but not all of them or none of them. Thanks all!

 

[Jimi77]

I'd probably start by making sure the connector at the back of the HU is tight.