Perhaps someone with more electrical engineering know-how can answer.
It's almost certainly a hardware issue. I don't know if it's the cable I'm using, some grounding issue, or what, but the problem is really annoying.
Full disclosure, I have a tmobile/at&t motherboard inside a N7105. I swapped it over last fall-ish because the N7105 motherboard developed a sleep of death problem that persisted through every rom I put on there, and even occurred when I was in recovery. Whatever, I can't get LTE on tmobile with this phone anyway, which is why I acquired a tmobile motherboard to swap in.
Perhaps it was always a problem, since I rarely use the headphone port. I got an unpleasant surprise a couple months ago when I tried- nothing but static through headphones. Long story short,
it's apparently some grounding issue? I followed the recommendations in that post. I still needed to smack it a little before it would work. But it more or less solved the issue.
I've been having wifi problems recently, and it may or may not be a consequence of the above issue. My wifi would simply stop detecting wifi signals. It would stop connecting, and then the wifi settings would eventually realize that it couldn't see any networks at all. Turning the wifi on/off or rebooting wouldn't bring it back. I keep solving this by disassembling my phone (poor thing, it's been disassembled so many times in the past month), letting it sit for a bit, and reassembling it. I'm slowly working out that putting screws in any slot other than right by the wifi antenna would eventually result in the lost wifi. It does work to bring the wifi back, and anything less doesn't. I don't know why. It might be a contact issue, but I can't see any difference between this and the N7105 motherboard.
In any case, this means that whatever grounding connection needed to make the headphone port work just isn't happening. That's fine, I still have my trusty rockboxed ipod.
But the wifi problem persists, and it's completely absent in the N7105 motherboard (but sleep of deeeeaaaaath). It could be that the Anker 10ft cable I recently got is no good or allowing too much electrical noise through or something. Maybe it doesn't like being charged too quickly. The wifi problems do occur more frequently when I use the Anker cable to charge.
To be honest, I'm not holding out much hope for a solution. The phone
is three years old, and even if I could have happily continued using it for another year or so, it is starting to show its age. I've been browsing Note 4s on ebay. It might be time for a change.
