iPhone does not get detected on older MacBook Pro I had to switch temporarily to a MacBook Pro 13 early 2011 model and when I'm connecting my iPhone 7+ or iPad, it's not getting detected nor charged.

Other USB devices like thumb drives or USB-microphones are working just fine.
If I put a voltcraft USB power converter between the iPhone/iPad and my MacBook Pro, the device is getting charged but it's still not getting detected in iTunes/duet. 
I already reset NVRAM (https://support.apple.com/en-us/HT204063) as suggested in similar posts here but that didn't fix anything and I don't know what else to try.

Any ideas?
Thanks
I've had the same problem before, and the following steps solved it for me:


Open iTunes
Plug the phone into the computer, and unlock the phone (Either with TouchID or Passcode Unlock)
A notification should popup on your phone saying "Trust This Computer?", click "Trust"
And finally, in iTunes and after a couple of seconds it should show up