iPhone 5 says "disabled, connect to iTunes" but iTunes says it "can't connect because of an unexpected error"
Focus on iTunes first. You need a working version of iTunes and can test with another phone if you aren’t sure your iTunes is ready to restore any phone and not just the one that’s disabled.


https://support.apple.com/en-us/HT201263


The disabled unlock will be your next hurdle, but get iTunes working unless you want to take the phone to another computer for erasing and determining the unlock status.


Unlocking a disabled iPhone