Stereo upgrade question

[Wicat3]

Hey everyone. I have a 2013 legacy that has a few issues I’m looking to fix but not sure how to proceed. It started shortly after buying it and I lost the aux port that I could plug my phone or iPod into. Most recently I’ve had issues with the Bluetooth connecting. I’ve noticed that my phone connects to the head unit roughly 45 minutes to an hour but very rarely is it any sooner. I’m not sure if it’s just age or somethings broken but I would like to try to fix it. My first thought was just put in an aftermarket head unit but I’m not sure how complicated that is versus just putting a stock head unit back into it.