Iphone 7 will not sync to Itunes

Hi all, I have been messing around with my phone on and off for a while. I have not been able to get it to connect to my MacBook Air.

Several months ago I messed around with it and tried to get it sync, I finally managed to get my photos to sync but my phone itself will not backup to my computer. During this time I made sure everything was up to date, my phone and my mac.

Today, I bought a new apple charging cable from the Apple store, thinking that maybe my off brand cord was the issue. It will connect to my computer, iTunes will recognize it and show the battery % correctly and attempt to backup, then it will kick off and say "iPhone was disconnected".

If I sync my iPad, which mind you is new and has almost nothing on it and only takes a minute or two to sync, will backup no problem.

When I was at the apple store today the tech checked my phone and said it had no communication issues wiring into their system.

I tried backing up my phone over wifi, but my phone will not appear in Finder-I tried the how-to and I check the boxes to make devices appear. Did not change anything.

What do I need to try next?

Thanks in advance,

Aaron