iPhone 4 update to ios7, not working error 21 and 3194

I recently update my iPhone 4 to ios7.

At first it worked great but all of a sudden it shut it self down, but I could just start it up again.

Over the course of 3 days this kept happening more and more often, until it shut down every time I wasn't doing anything on the device.

The day after that it wouldn't start anymore, only when I connected it to a charger it would come on again.

Then it would just reboot over and over again, with only the apple logo appearing on screen.

When I tried to put it in recovery mode and connect it to itunes it would stop after a while and never fully restore.

So I tried the same thing in DFU Mode and did a restore.

It didn't work and gave me an error 21 and after a while an error 3194.

I have also tried pressing shift + restore in itunes to manually put in an ipsw file, this didn't work as well (probably because of the downgrade restrictions Apple has put up after ios7 came out).

I was doubting if it was either a software or a hardware problem, but all the people I have talked to (friends, official apple store Amsterdam, although the genius bar was too crowded so I couldn't to someone there) say it is probably a software issue.

I think I am pretty much out of options here, and couldn't find a completely similar case in this community.

So I hope one of you knows more about this issue!

You would really help me out.